Pickup 2 Upstream NuttX PX4 contributions

1) Ensure if CONFIG_SERIAL_DMA is set that cdcacm uart_ops is initalized
     with correct functions in correct slots.
     This was detected only with PX4 build flags
  2) C&P error from F7 would prevent CONFIG_STM32_SERIALBRK_BSDCOMPAT ifdefed
     code from being included.

nuttx-patches/wip_inflight_to_upstream.patch

@@ -0,0 +1,35 @@
+diff --git NuttX/nuttx/drivers/usbdev/cdcacm.c NuttX/nuttx/drivers/usbdev/cdcacm.c
+index 64e2e68..15f92dd 100644
+--- NuttX/nuttx/drivers/usbdev/cdcacm.c
++++ NuttX/nuttx/drivers/usbdev/cdcacm.c
+@@ -243,6 +243,12 @@ static const struct uart_ops_s g_uartops =
+ #ifdef CONFIG_SERIAL_IFLOWCONTROL
+   cdcuart_rxflowcontrol, /* rxflowcontrol */
+ #endif
++#ifdef CONFIG_SERIAL_DMA
++  NULL,                  /* dmasend */
++  NULL,                  /* dmareceive */
++  NULL,                  /* dmarxfree */
++  NULL,                  /* dmatxavail */
++#endif
+   NULL,                  /* send */
+   cdcuart_txint,         /* txinit */
+   NULL,                  /* txready */
+diff --git NuttX/nuttx/arch/arm/src/stm32/stm32_serial.c NuttX/nuttx/arch/arm/src/stm32/stm32_serial.c
+index 644c810..10919e8 100644
+--- NuttX/nuttx/arch/arm/src/stm32/stm32_serial.c
++++ NuttX/nuttx/arch/arm/src/stm32/stm32_serial.c
+@@ -1945,11 +1945,11 @@ static int up_interrupt_common(struct up_dev_s *priv)
+ static int up_ioctl(struct file *filep, int cmd, unsigned long arg)
+ {
+ #if defined(CONFIG_SERIAL_TERMIOS) || defined(CONFIG_SERIAL_TIOCSERGSTRUCT) \
+-    || defined(CONFIG_STM32F7_SERIALBRK_BSDCOMPAT)
++    || defined(CONFIG_STM32_SERIALBRK_BSDCOMPAT)
+   struct inode      *inode = filep->f_inode;
+   struct uart_dev_s *dev   = inode->i_private;
+ #endif
+-#if defined(CONFIG_SERIAL_TERMIOS) || defined(CONFIG_STM32F7_SERIALBRK_BSDCOMPAT)
++#if defined(CONFIG_SERIAL_TERMIOS) || defined(CONFIG_STM32_SERIALBRK_BSDCOMPAT)
+   struct up_dev_s   *priv  = (struct up_dev_s *)dev->priv;
+ #endif
+   int                ret    = OK;