platform: add Radxa ROCK 3B platform support

Signed-off-by: Nascs <nascs@radxa.com>

include/arm/radxa_rock_3b.h

@@ -0,0 +1,30 @@
+/*
+ * Author: Nascs <nascs@radxa.com>
+ * Copyright (c) Radxa Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "mraa_internal.h"
+
+#define MRAA_RADXA_ROCK_3B_GPIO_COUNT 28
+#define MRAA_RADXA_ROCK_3B_I2C_COUNT  3
+#define MRAA_RADXA_ROCK_3B_SPI_COUNT  1
+#define MRAA_RADXA_ROCK_3B_UART_COUNT 6
+#define MRAA_RADXA_ROCK_3B_PWM_COUNT  11
+#define MRAA_RADXA_ROCK_3B_AIO_COUNT  1
+#define MRAA_RADXA_ROCK_3B_PIN_COUNT  40
+#define PLATFORM_NAME_RADXA_ROCK_3B   "Radxa ROCK 3 Model B"
+
+mraa_board_t *
+        mraa_radxa_rock_3b();
+
+#ifdef __cplusplus
+}
+#endif