[PATCH] swsusp: fix panic when signature can't be read

Do not panic a machine when swsusp signature can't be read.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>