x86: Fix typo in arch/x86/mm/kmmio.c

Signed-off-by: Shaun Patterson <shaunpatterson@gmail.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: pq@iki.fi
LKML-Reference: <1260027694.10074.170.camel@linux-4lgc.site>
Signed-off-by: Ingo Molnar <mingo@elte.hu>