Rover: use RC_CALIB_MIN_LIMIT_PWM and RC_CALIB_MAX_LIMIT_PWM

Rover/AP_Arming.cpp

@@ -19,11 +19,11 @@ bool AP_Arming_Rover::rc_calibration_checks(const bool display_failure)
         const RC_Channel *channel = channels[i];
         const char *channel_name = channel_names[i];
         // check if radio has been calibrated
-        if (channel->get_radio_min() > 1300) {
+        if (channel->get_radio_min() > RC_Channel::RC_CALIB_MIN_LIMIT_PWM) {
             check_failed(ARMING_CHECK_RC, display_failure, "%s radio min too high", channel_name);
             return false;
         }
-        if (channel->get_radio_max() < 1700) {
+        if (channel->get_radio_max() < RC_Channel::RC_CALIB_MAX_LIMIT_PWM) {
             check_failed(ARMING_CHECK_RC, display_failure, "%s radio max too low", channel_name);
             return false;
         }