AP_HAL_ChibiOS: wrap define AP_XX_ENABLED AP_PERIPH_YY_ENABLED inside ifndef-endif

We should be only defining these if they are already not defined.

Author: shiv-tyagi

libraries/AP_HAL_ChibiOS/hwdef/scripts/defaults_periph.h

@@ -360,12 +360,18 @@
 #define AP_AHRS_ENABLED AP_PERIPH_AHRS_ENABLED
 #define AP_COMPASS_ENABLED AP_PERIPH_MAG_ENABLED
 #define AP_BARO_ENABLED AP_PERIPH_BARO_ENABLED
+#ifndef AP_RANGEFINDER_ENABLED
 #define AP_RANGEFINDER_ENABLED AP_PERIPH_RANGEFINDER_ENABLED
+#endif
 #define AP_INERTIALSENSOR_ENABLED AP_PERIPH_IMU_ENABLED
 #define AP_INERTIALSENSOR_ALLOW_NO_SENSORS AP_PERIPH_IMU_ENABLED
 #define AP_RTC_ENABLED AP_PERIPH_RTC_ENABLED
+#ifndef AP_RCPROTOCOL_ENABLED
 #define AP_RCPROTOCOL_ENABLED AP_PERIPH_RCIN_ENABLED
+#endif
+#ifndef AP_RPM_ENABLED
 #define AP_RPM_ENABLED AP_PERIPH_RPM_ENABLED
+#endif
 
 /*
  * GPS Backends - we selectively turn backends on.