Implement 'agc' reset for SX126x & LR11x0 chip families (#9705)

* Implement 'agc' reset for SX126x chip family

There's no actual agc on SX126x chips but you can reset the analog
registers by doing a warm sleep & running calibration.

* Address PR comments & implement for LR11x0 too

* calibrate for configured frequency band

* Gate LR11X0_AGC_RESET

src/mesh/RadioLibInterface.cpp

@@ -529,6 +529,11 @@ void RadioLibInterface::pollMissedIrqs()
     }
 }
 
+void RadioLibInterface::resetAGC()
+{
+    // Base implementation: no-op. Override in chip-specific subclasses.
+}
+
 void RadioLibInterface::checkRxDoneIrqFlag()
 {
     if (iface->checkIrq(RADIOLIB_IRQ_RX_DONE)) {