drm/vc4: add extcon hdmi connection uevent

drm/vc4: add extcon hdmi connection uevent

Add extcon hdmi connection and disconnection uevent when extcon
module is enabled.

The vc4_hdmi detection is done by polling way, so extcon uevent
for connection is a bit slow after changing real hdmi cable state.

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
[mszyprow: this is a squashed set of the following patches
 from platform/kernel/linux-rpi 'tizen' (c4f85fdcd893) branch:
 drm/vc4: add extcon hdmi connection uevent
 drm/vc4: hdmi: Fix hotplug extcon uevent to works
 ported and adapted to Linux v6.6 kernel base]

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Change-Id: I2a825241cd72befd1f75bd094405f719d4b20638