px4fmu-v5:Comment and define SAFETY LED and Button so FMU can use

Safety Switch is HW version dependent on having an PX4IO
  So we init to a benign state with the _INIT definition
  and provide the the non _INIT one for the driver to make a run time
  decision to use it.

  We also define the FMU GPIO_BTN_SAFETY and GPIO_LED_SAFETY alias
  so the px4fmu will drrive will be built with the safety switch
  code at compile time and have runtime control via the manifest

src/drivers/boards/px4fmu-v5/board_config.h

@@ -555,13 +555,20 @@
 
 #define GPIO_RSSI_IN                       /* PB0  */ (GPIO_INPUT|GPIO_PULLUP|GPIO_PORTB|GPIO_PIN0)
 #define GPIO_RSSI_IN_INIT                  /* PB0  */ 0 /* Leave as ADC RSSI_IN */
-/* Change GPIO_nSAFETY_SWITCH_LED_OUT to
- * (GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTE|GPIO_PIN12)
- * to enable the safety switch led on FMU
+
+/* Safety Switch is HW version dependent on having an PX4IO
+ * So we init to a benign state with the _INIT definition
+ * and provide the the non _INIT one for the driver to make a run time
+ * decision to use it.
  */
-#define GPIO_nSAFETY_SWITCH_LED_OUT        /* PE12 */ (GPIO_INPUT|GPIO_FLOAT|GPIO_PORTE|GPIO_PIN12)
 #define GPIO_nSAFETY_SWITCH_LED_OUT_INIT   /* PE12 */ (GPIO_INPUT|GPIO_FLOAT|GPIO_PORTE|GPIO_PIN12)
+#define GPIO_nSAFETY_SWITCH_LED_OUT        /* PE12 */ (GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTE|GPIO_PIN12)
+
+/* Enable the FMU to control it if there is no px4io fixme:This should be BOARD_SAFETY_LED(__ontrue) */
+#define GPIO_LED_SAFETY GPIO_nSAFETY_SWITCH_LED_OUT
 #define GPIO_SAFETY_SWITCH_IN              /* PE10 */ (GPIO_INPUT|GPIO_PULLUP|GPIO_PORTE|GPIO_PIN10)
+/* Enable the FMU to use the switch it if there is no px4io fixme:This should be BOARD_SAFTY_BUTTON() */
+#define GPIO_BTN_SAFETY GPIO_SAFETY_SWITCH_IN /* Enable the FMU to control it if there is no px4io */
 
 /* Power switch controls ******************************************************/