Fix remote LNA toggle bugs: correct register comparison, add missing implementations, wire up companion radio

getRxBoostedGain was returned true because both 0x94 (power saving) and
0x96 (boosted gain = 1) return true

variants/heltec_v2/target.h

@@ -27,5 +27,3 @@ uint32_t radio_get_rng_seed();
 void radio_set_params(float freq, float bw, uint8_t sf, uint8_t cr);
 void radio_set_tx_power(int8_t dbm);
 mesh::LocalIdentity radio_new_identity();
-
-bool radio_get_rx_boosted_gain_mode();