drm/i915: Add local adjusted_mode variable

Clean up the eyesore in intel_get_transcoder_timings() a
bit by adding a local 'adjusted_mode' variable.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230213225258.2127-9-ville.syrjala@linux.intel.com


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