drm/i915: Constify the state arguments to the color management stuff

Pass the crtc state etc. as const to the color management commit
functions. And while at it polish some of the local variables.

v2: Rebase
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190205160848.24662-4-ville.syrjala@linux.intel.comReviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

drivers/gpu/drm/i915/i915_drv.h

@@ -323,8 +323,8 @@ struct drm_i915_display_funcs {
 	/* display clock increase/decrease */
 	/* pll clock increase/decrease */
 
-	void (*load_csc_matrix)(struct intel_crtc_state *crtc_state);
-	void (*load_luts)(struct intel_crtc_state *crtc_state);
+	void (*load_csc_matrix)(const struct intel_crtc_state *crtc_state);
+	void (*load_luts)(const struct intel_crtc_state *crtc_state);
 };
 
 #define CSR_VERSION(major, minor)	((major) << 16 | (minor))

drivers/gpu/drm/i915/intel_drv.h

@@ -2389,8 +2389,8 @@ int intel_plane_atomic_check_with_state(const struct intel_crtc_state *old_crtc_
 /* intel_color.c */
 void intel_color_init(struct intel_crtc *crtc);
 int intel_color_check(struct intel_crtc_state *crtc_state);
-void intel_color_set_csc(struct intel_crtc_state *crtc_state);
-void intel_color_load_luts(struct intel_crtc_state *crtc_state);
+void intel_color_set_csc(const struct intel_crtc_state *crtc_state);
+void intel_color_load_luts(const struct intel_crtc_state *crtc_state);
 
 /* intel_lspcon.c */
 bool lspcon_init(struct intel_digital_port *intel_dig_port);