ESP32c3: Migrate variants to new structure (#7342)

variants/esp32c3/ai-c3/variant.h

@@ -0,0 +1,32 @@
+#define SDA 0
+#define SCL 1
+#define I2C_SDA SDA
+#define I2C_SCL SCL
+
+#define BUTTON_PIN 9 // BOOT button
+#define LED_PIN 30   // RGB LED
+
+#define USE_RF95
+#define LORA_SCK 4
+#define LORA_MISO 5
+#define LORA_MOSI 6
+#define LORA_CS 7
+
+#define LORA_DIO0 10
+#define LORA_DIO1 3
+#define LORA_RESET 2
+
+// WaveShare Core1262-868M
+// https://www.waveshare.com/wiki/Core1262-868M
+#define USE_SX1262
+#define SX126X_CS LORA_CS
+#define SX126X_DIO1 LORA_DIO1
+#define SX126X_BUSY 10
+#define SX126X_RESET LORA_RESET
+
+#define SX126X_DIO2_AS_RF_SWITCH // use DIO2 as RF switch
+#define SX126X_DIO3_TCXO_VOLTAGE 1.8
+
+#define HAS_GPS 0
+#undef GPS_RX_PIN
+#undef GPS_TX_PIN