drm/i915: Do panel VBT init early if the VBT declares an explicit panel type

drm/i915: Do panel VBT init early if the VBT declares an explicit panel type

Lots of ADL machines out there with bogus VBTs that declare
two eDP child devices. In order for those to work we need to
figure out which power sequencer to use before we try the EDID
read. So let's do the panel VBT init early if we can, falling
back to the post-EDID init otherwise.

The post-EDID init panel_type=0xff approach of assuming the
power sequencer should already be enabled doesn't really work
with multiple eDP panels, and currently we just end up using
the same power sequencer for both eDP ports, which at least
confuses the wakeref tracking, and potentially also causes us
to toggle the VDD for the panel when we should not.

Cc: Animesh Manna <[email protected]>
Reviewed-by: Jani Nikula <[email protected]>
Signed-off-by: Ville Syrjälä <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]