drm/i915: Move LPT PCH readout code

drm/i915: Move LPT PCH readout code

Nuke the hsw_get_ddi_port_state() eyesore by putting the
readout code into intel_pch_display.c, and calling it directly
from hsw_crt_get_config().

Note that the nuked TRANS_DDI_FUNC_CTL readout from
hsw_get_ddi_port_state() is now etirely redundant since we
get called from the encoder->get_config() so we already know
we're dealing with the correct DDI port. Previously the
code was called from a place where that wasn't known so
it had to checked manually.

v2: Clarify the TRANS_DDI_FUNC_CTL change (Dave)
    Nuke the now unused *TRANS_DDI_FUNC_CTL_VAL_TO_PORT() (Dave)

Cc: Dave Airlie <airlied@redhat.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018153525.21597-1-ville.syrjala@linux.intel.com
Reviewed-by: Dave Airlie <airlied@redhat.com>