init: fix wording error in mm_init comment

s/countinuous/contiguous/, reword sentence.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>