kcore: fix test for end of list

kcore: fix test for end of list

commit 4fd2c20d964a8fb9861045f1022475c9d200d684 upstream.

"m" is never NULL here.  We need a different test for the end of list
condition.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Leonardo Chiquitto <leonardo.lists@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>