Fix LoRaWAN PHY settings for SX126x driver

* Set preamble length to 8 symbols
* Set polarity to inverted for received messages

Author: jbeaurivage

embassy-lora/src/sx126x/mod.rs

@@ -87,7 +87,7 @@ where
                     config.rf.spreading_factor.into(),
                     config.rf.bandwidth.into(),
                     config.rf.coding_rate.into(),
-                    4,
+                    8,
                     false,
                     true,
                     false,
@@ -119,14 +119,14 @@ where
                     config.spreading_factor.into(),
                     config.bandwidth.into(),
                     config.coding_rate.into(),
-                    4,
+                    8,
                     4,
                     false,
                     0u8,
                     true,
                     false,
                     0,
-                    false,
+                    true,
                     true,
                 )
                 .await?;