drm/i915: fix VDD state tracking after system resume

Just like during booting the BIOS can leave the VDD bit enabled after
system resume. So apply the same state sanitization there too. This
fixes a problem where after resume the port power domain refcount gets
unbalanced.

v2:
- unchanged
v3:
- call edp sanitizing from the encoder reset handler (Daniel)

Reported-and-tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>