drm/i915/tv: Drop redundant null checks

Neither 'tv_mode' or 'color_conversion' can be NULL,
so drop the pointless checks.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231207193441.20206-9-ville.syrjala@linux.intel.com


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