Global: remove get_fd() from Device API

This was there for compatibility with I2CDriver and SPIDriver. We don't
use them anymore so we can remove the compat method.

libraries/AP_HAL/Device.h

@@ -141,12 +141,6 @@ public:
      */
     virtual bool unregister_callback(PeriodicHandle h) { return false; }
 
-    /*
-     * Temporary method to get the fd used by this device: it's here only for
-     * allowing to convert old drivers to this new interface
-     */
-    virtual int get_fd() = 0;
-
     /**
      * Some devices connected on the I2C or SPI bus require a bit to be set on
      * the register address in order to perform a read operation. This sets a

libraries/AP_HAL/I2CDevice.h

@@ -66,9 +66,6 @@ public:
     /* See Device::adjust_periodic_callback() */
     virtual bool adjust_periodic_callback(
         Device::PeriodicHandle h, uint32_t period_usec) override = 0;
-
-    /* See Device::get_fd() */
-    virtual int get_fd() override = 0;
 };
 
 class I2CDeviceManager {

libraries/AP_HAL/SPIDevice.h

@@ -56,8 +56,6 @@ public:
     /* See Device::adjust_periodic_callback() */
     virtual bool adjust_periodic_callback(
         PeriodicHandle h, uint32_t period_usec) override { return false; }
-
-    virtual int get_fd() override = 0;
 };
 
 class SPIDeviceManager {

libraries/AP_HAL_Empty/I2CDevice.h

@@ -77,9 +77,6 @@ public:
     {
         return true;
     }
-
-    /* See AP_HAL::Device::get_fd() */
-    int get_fd() { return -1; }
 };
 
 class I2CDeviceManager : public AP_HAL::I2CDeviceManager {

libraries/AP_HAL_Empty/SPIDevice.h

@@ -69,9 +69,6 @@ public:
         return nullptr;
     }
 
-    /* See AP_HAL::Device::get_fd() */
-    int get_fd() override { return -1; }
-
 private:
     Semaphore _semaphore;
 };

libraries/AP_HAL_Linux/I2CDevice.cpp

@@ -237,11 +237,6 @@ AP_HAL::Semaphore *I2CDevice::get_semaphore()
     return &_bus.sem;
 }
 
-int I2CDevice::get_fd()
-{
-    return _bus.fd;
-}
-
 AP_HAL::Device::PeriodicHandle I2CDevice::register_periodic_callback(
     uint32_t period_usec, AP_HAL::Device::PeriodicCb cb)
 {

libraries/AP_HAL_Linux/I2CDevice.h

@@ -76,9 +76,6 @@ public:
     bool adjust_periodic_callback(
         AP_HAL::Device::PeriodicHandle h, uint32_t period_usec) override;
 
-    /* See AP_HAL::Device::get_fd() */
-    int get_fd() override;
-
 protected:
     I2CBus &_bus;
     uint8_t _address;

libraries/AP_HAL_Linux/SPIDevice.cpp

@@ -353,11 +353,6 @@ AP_HAL::Semaphore *SPIDevice::get_semaphore()
     return &_bus.sem;
 }
 
-int SPIDevice::get_fd()
-{
-    return _bus.fd;
-}
-
 AP_HAL::Device::PeriodicHandle SPIDevice::register_periodic_callback(
     uint32_t period_usec, AP_HAL::Device::PeriodicCb cb)
 {

libraries/AP_HAL_Linux/SPIDevice.h

@@ -58,9 +58,6 @@ public:
     bool adjust_periodic_callback(
         AP_HAL::Device::PeriodicHandle h, uint32_t period_usec) override;
 
-    /* See AP_HAL::Device::get_fd() */
-    int get_fd() override;
-
 protected:
     SPIBus &_bus;
     SPIDesc &_desc;

libraries/AP_HAL_PX4/I2CDevice.h

@@ -69,9 +69,6 @@ public:
         return false;
     }
 
-    // this makes no sense on PX4
-    int get_fd() override { return -1; }
-
     AP_HAL::Semaphore* get_semaphore() override { return &semaphore; }
 
 private:

libraries/AP_HAL_VRBRAIN/I2CDevice.h

@@ -69,9 +69,6 @@ public:
         return false;
     }
 
-    // this makes no sense on VRBRAIN
-    int get_fd() override { return -1; }
-
     AP_HAL::Semaphore* get_semaphore() override { return &semaphore; }
 
 private: