variants: RAK4631: Enable RF module reset pin

There is no reason to not use the reset pin as the RAK4630/31 module
has it connected internally.

Signed-off-by: Frieder Schrempf <frieder@fris.de>

Author: fschrempf

variants/rak4631/variant.h

@@ -147,7 +147,7 @@ extern "C"
 // LoRa radio module pins for RAK4631
 #define  P_LORA_DIO_1 (47)
 #define  P_LORA_NSS (42)
-#define  P_LORA_RESET (-1)
+#define  P_LORA_RESET (38)
 #define  P_LORA_BUSY (46)
 #define  P_LORA_SCLK (43)
 #define  P_LORA_MISO (45)