Add board support for Dialog DA1469x-dk-pro

This adds source files that allow to run TinyUSB stack on DA1469x-dk-pro board.
Source files .c .S and .ld are taken from Apache Mynewt repository.
Those files were stripped to allow starting board without Mynewt os.

hw/bsp/board_mcu.h

@@ -113,6 +113,9 @@
 #elif CFG_TUSB_MCU == OPT_MCU_ESP32S2
   // no header needed
 
+#elif CFG_TUSB_MCU == OPT_MCU_DA1469X
+  #include "DA1469xAB.h"
+
 #else
   #error "Missing MCU header"
 #endif