add raspi3 mbox driver

bsp/raspberry-pi/raspi3-64/driver/SConscript

@@ -6,6 +6,7 @@ cwd     = GetCurrentDir()
 src     = Split('''
 board.c
 drv_uart.c
+mbox.c
 ''')
 CPPPATH = [cwd]
 

bsp/raspberry-pi/raspi3-64/driver/board.c

@@ -99,6 +99,7 @@ void rt_hw_board_init(void)
     armv8_map(0x3f200000, 0x3f200000, 0x16000, MEM_ATTR_IO);//uart
     armv8_map(0x40000000, 0x40000000, 0x1000, MEM_ATTR_IO);//core timer
     armv8_map(0x3F300000, 0x3F300000, 0x1000, MEM_ATTR_IO);//sdio
+    armv8_map(0xc00000, 0xc00000, 0x1000, MEM_ATTR_IO);//mbox
     mmu_enable();
     
     /* initialize hardware interrupt */

bsp/raspberry-pi/raspi3-64/driver/mbox.c

@@ -17,10 +17,6 @@ volatile unsigned int *mbox = (volatile unsigned int *) MBOX_ADDR;
 /**
  * Make a mailbox call. Returns 0 on failure, non-zero on success
  */
-void init_mbox_mmu_map(){
-	rt_hw_change_mmu_table(MBOX_ADDR, 96, MBOX_ADDR, STRONG_ORDER_MEM);
-}
-
 int mbox_call(unsigned char ch, int mmu_enable)
 {
     unsigned int r = (((MBOX_ADDR)&~0xF) | (ch&0xF));