fanotify: only destroy mark when both mask and ignored_mask are cleared

In fanotify_mark_remove_from_mask() a mark is destroyed if only one of
both bitmasks (mask or ignored_mask) of a mark is cleared.  However the
other mask may still be set and contain information that should not be
lost.  So only destroy a mark if both masks are cleared.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>