media: cec-notifier: Get notifier by device and connector name

In non device-tree world, we can need to get the notifier by the driver
name directly and eventually defer probe if not yet created.

This patch adds a variant of the get function by using the device name
instead and will not create a notifier if not yet created.

But the i915 driver exposes at least 2 HDMI connectors, this patch also
adds the possibility to add a connector name tied to the notifier device
to form a tuple and associate different CEC controllers for each HDMI
connectors.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>