drm/i915: Relocate pipe_config_mismatch()

Hoist pipe_config_mismatch() upwards a bit so that it can get
reused by the other mismatch() functions.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240215164055.30585-11-ville.syrjala@linux.intel.com


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