Use <stand.h> instead of <inttypes.h> and <stdio.h> in boot code.

In the freestanding boot compile environment, standard headers are not
available.  Curiously, only building with clang exposed this as compiles
with external GCC still succeeded.

Sponsored by:	DARPA / AFRL

stand/mips/beri/common/sdcard.c

@@ -33,8 +33,7 @@
 #include <sys/types.h>
 #include <sys/endian.h>
 
-#include <inttypes.h>
-#include <stdio.h>
+#include <stand.h>
 
 
 /*