Impact: cleanup

This patch moves the init_memory_mapping() function to common mm/init.c.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1236257708-27269-14-git-send-email-penberg@cs.helsinki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>