AP_Notify: rename member to initialized

We are not only checking if there was an error, but if it was already
initialized.  Let's make it explicit by inverting the value we store.

libraries/AP_Notify/ToneAlarm_Linux.cpp

@@ -36,12 +36,12 @@ extern const AP_HAL::HAL& hal;
 bool ToneAlarm_Linux::init()
 {
     // open the tone alarm device
-    err = !hal.util->toneAlarm_init();
-    if (err) {
+    _initialized = hal.util->toneAlarm_init();
+    if (!_initialized) {
         hal.console->printf("AP_Notify: Failed to initialise ToneAlarm");
         return false;
     }
-    
+
     // set initial boot states. This prevents us issueing a arming
     // warning in plane and rover on every boot
     flags.armed = AP_Notify::flags.armed;
@@ -61,7 +61,7 @@ bool ToneAlarm_Linux::play_tune(uint8_t tune_number)
 void ToneAlarm_Linux::update()
 {
     // exit immediately if we haven't initialised successfully
-    if (err) {
+    if (!_initialized) {
         return;
     }
 

libraries/AP_Notify/ToneAlarm_Linux.h

@@ -23,9 +23,6 @@
 class ToneAlarm_Linux: public NotifyDevice
 {
 public:
-    ToneAlarm_Linux() : err(true)
-    { }
-
     /// init - initialised the tone alarm
     bool init(void);
 
@@ -36,7 +33,7 @@ private:
     /// play_tune - play one of the pre-defined tunes
     bool play_tune(uint8_t tune_number);
 
-    bool err;
+    bool _initialized = false;
 
     /// tonealarm_type - bitmask of states we track
     struct tonealarm_type {