Allow calling cec_notifier_set_phys_addr and
cec_notifier_set_phys_addr_from_edid with a NULL notifier, in which
case these functions do nothing.
Add a cec_notifier_phys_addr_invalidate helper function (the notifier
equivalent of cec_phys_addr_invalidate).
These changes simplify drm CEC driver support.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>