drm/i915: Remove pointless register read

We just wrote the EDP transcoder's VTOTAL register a few lines
earlier, so instead of reading it back out again let's just
generate the same value for the transocder B/C register.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230213225258.2127-13-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>