drm/i915/mso: add splitter state check

For starters, we expect the state to be zero, as we don't enable MSO
anywhere.

v2: Refer to splitter.

Cc: Nischal Varide <nischal.varide@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/459a332f3cdce941c57312150872559db68f88c1.1614682842.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_display.c

@@ -9339,6 +9339,10 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
 	PIPE_CONF_CHECK_I(dsc.dsc_split);
 	PIPE_CONF_CHECK_I(dsc.compressed_bpp);
 
+	PIPE_CONF_CHECK_BOOL(splitter.enable);
+	PIPE_CONF_CHECK_I(splitter.link_count);
+	PIPE_CONF_CHECK_I(splitter.pixel_overlap);
+
 	PIPE_CONF_CHECK_I(mst_master_transcoder);
 
 	PIPE_CONF_CHECK_BOOL(vrr.enable);