drm/i915: Pass encoder all the way to intel_ddi_transcoder_func_reg_val_get()

Pass the encoder all the way down to
intel_ddi_transcoder_func_reg_val_get(). Allows us eliminate the
intel_ddi_get_crtc_encoder() eyesore.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200417134720.16654-4-ville.syrjala@linux.intel.com


Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Jani Nikula <jani.nikula@intel.com>