treewide: Fix typo compatability -> compatibility

Even though 'compatability' has a dedicated entry in the Wiktionary,
it's listed as 'Mispelling of compatibility'. Fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> for the atomic_helper.c
Signed-off-by: Jiri Kosina <jkosina@suse.com>