sandbox: Change md command to use map_physmem

Sandbox wants to support commands which use memory. The map_physmen()
call provides this feature, so should be used more consistently in
U-Boot.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Tested-by: Matthias Weisser <weisserm@arcor.de>
diff --git a/common/cmd_mem.c b/common/cmd_mem.c
index 28476d7..461ee19 100644
--- a/common/cmd_mem.c
+++ b/common/cmd_mem.c
@@ -33,6 +33,7 @@
 #include <dataflash.h>
 #endif
 #include <watchdog.h>
+#include <asm/io.h>
 
 #ifdef	CMD_MEM_DEBUG
 #define	PRINTF(fmt,args...)	printf (fmt ,##args)
@@ -141,9 +142,13 @@
 # endif
 
 	{
+		ulong bytes = size * length;
+		void *buf = map_physmem(addr, bytes, MAP_WRBACK);
+
 		/* Print the lines. */
-		print_buffer(addr, (void*)addr, size, length, DISP_LINE_LEN/size);
-		addr += size*length;
+		print_buffer(addr, buf, size, length, DISP_LINE_LEN / size);
+		addr += bytes;
+		unmap_physmem(buf, bytes);
 	}
 #endif