drm/vc4/vc4_hdmi: fill in connector info

Fill in the connector info, allowing userspace to associate
the CEC device with the drm connector.

Tested on a Raspberry Pi 3B.

Signed-off-by: Dariusz Marcinkiewicz <darekm@google.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Tested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20190823112427.42394-2-hverkuil-cisco@xs4all.nl