SX126x: Try next Interface when chip not found (#2363)

* If chip was not found, return false for init()

* SX1268: Only overwrite frequency when out of bounds
Happens when region is still UNSET

src/mesh/SX1268Interface.cpp

@@ -6,4 +6,13 @@ SX1268Interface::SX1268Interface(RADIOLIB_PIN_TYPE cs, RADIOLIB_PIN_TYPE irq, RA
                                  SPIClass &spi)
     : SX126xInterface(cs, irq, rst, busy, spi)
 {
+}
+
+float SX1268Interface::getFreq()
+{
+    // Set frequency to default of EU_433 if outside of allowed range (e.g. when region is UNSET)
+    if (savedFreq < 410 || savedFreq > 810)
+        return 433.125f;
+    else
+        return savedFreq;
 }