drm/edid: Fix add_cea_modes() style issues

A few styles issues have crept in here, fix them before touching this
code again.

v2: constify arguments that can be (Ville Syrjälä)
v3: constify, but better (Ville Syrjälä)
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@gmail.com>

drivers/gpu/drm/drm_edid.c

@@ -2441,10 +2441,11 @@ add_alternate_cea_modes(struct drm_connector *connector, struct edid *edid)
 }
 
 static int
-do_cea_modes (struct drm_connector *connector, u8 *db, u8 len)
+do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
 {
 	struct drm_device *dev = connector->dev;
-	u8 * mode, cea_mode;
+	const u8 *mode;
+	u8 cea_mode;
 	int modes = 0;
 
 	for (mode = db; mode < db + len; mode++) {
@@ -2501,8 +2502,9 @@ cea_db_offsets(const u8 *cea, int *start, int *end)
 static int
 add_cea_modes(struct drm_connector *connector, struct edid *edid)
 {
-	u8 * cea = drm_find_cea_extension(edid);
-	u8 * db, dbl;
+	const u8 *cea = drm_find_cea_extension(edid);
+	const u8 *db;
+	u8 dbl;
 	int modes = 0;
 
 	if (cea && cea_revision(cea) >= 3) {
@@ -2516,7 +2518,7 @@ add_cea_modes(struct drm_connector *connector, struct edid *edid)
 			dbl = cea_db_payload_len(db);
 
 			if (cea_db_tag(db) == VIDEO_BLOCK)
-				modes += do_cea_modes (connector, db+1, dbl);
+				modes += do_cea_modes(connector, db + 1, dbl);
 		}
 	}