drm/i915/hdmi: stop using connector->override_edid

The connector->override_edid flag is strictly for EDID override debugfs
management, and drivers have no business using it.

The check for override_edid was added in commit 30190629 ("drm/i915:
Ignore TMDS clock limit for DP++ when EDID override is set") to
facilitate mode list cross-checking against modes in override EDID when
the connector in question isn't even connected. The dual mode detect
fallback would do VBT based limiting in this case.

Instead of override EDID, check for connector forcing in the fallback.

v2: Simply use !connector->force (Ville)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c8b45867cf37134ab40be23e22825ca45adc6041.1666614699.git.jani.nikula@intel.com