MIPS: Add missing definition for MADV_HWPOISON.

Thanks to Joseph S. Myers for reporting this.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: "Joseph S. Myers" <joseph@codesourcery.com>
Patchwork: http://patchwork.linux-mips.org/patch/723/
1 file changed