[POWERPC] Make xmon_write accept a const buffer

Because xmon_write doesn't change the buffer, we should add 'const'
qualifier to the argument which points it.

Signed-off-by: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2 files changed