drm/display: Move HDMI helpers into display-helper module

Move DRM's HMDI helpers into the display/ subdirectoy and add it
to DRM's display helpers. Update all affected drivers. No functional
changes.

The HDMI helpers were implemented in the EDID and connector code, but
are actually unrelated. With the move to the display-helper library, we
can remove the dependency on drm_edid.{c,h} in some driver's HDMI source
files.

Several of the HDMI helpers remain in EDID code because both share parts
of their implementation internally. With better refractoring of the EDID
code, those HDMI helpers could be moved into the display-helper library
as well.

v3:
* fix Kconfig dependencies (Javier)
v2:
* reduce HDMI helpers to avoid exporting functions (Jani)
* fix include statements (Jani, Javier)
* update Kconfig symbols

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220421073108.19226-8-tzimmermann@suse.de