Remove unused RX boosted gain mode functions and related preprocessor directives across multiple variants

variants/lilygo_tbeam_1w/platformio.ini

@@ -8,7 +8,6 @@ build_flags =
 
   ; Radio - SX1262 with high-power PA (32dBm max output)
   ; Note: Set SX1262 output to 22dBm max, external PA provides additional gain
-  -D USE_SX1262
   -D RADIO_CLASS=CustomSX1262
   -D WRAPPER_CLASS=CustomSX1262Wrapper
   -D P_LORA_DIO_1=1