drm/vc4: hdmi: Depends on CONFIG_PM

drm/vc4: hdmi: Depends on CONFIG_PM

We already depend on runtime PM to get the power domains and clocks for
most of the devices supported by the vc4 driver, so let's just select it
to make sure it's there.

Link: https://lore.kernel.org/r/20220629123510.1915022-38-maxime@cerno.tech
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
(cherry picked from commit f1bc386b319e93e56453ae27e9e83817bb1f6f95)
Signed-off-by: Maxime Ripard <maxime@cerno.tech>