Remove unused variable in ftmsbike.h

Removed unused variable 'usdc_d700_ftms_frames_received'.

Author: cagnulein

src/devices/ftmsbike/ftmsbike.h

@@ -182,7 +182,6 @@ class ftmsbike : public bike {
     bool ZIPRO_RAVE = false;
     bool SPEEDRACEX = false;
     bool USDC_D700 = false;
-    int usdc_d700_ftms_frames_received = 0;
 
     uint8_t secondsToResetTimer = 5;