drm/i915: Drop pointless i830 PIPECONF read

drm/i915: Drop pointless i830 PIPECONF read

Reading the PIPECONF enable bit out from the hardware
in i9xx_set_pipeconf() on i830 is pointless as the bit should
always be set since we keep both pipes constantly running on
i830. Drop the pointless read and just always keep the bit set.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220202111616.1579-4-ville.syrjala@linux.intel.com
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>