drm/edid: abstract OUI conversion to 24-bit int

Replace the open coded OUI conversion from three bytes to a 24-bit int,
as we'll be adding one more user shortly. No functional changes.

Side note: CTA-861 format has the OUI bytes in reverse order.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Acked-by: Maxime Ripard <maxime@cerno.tech>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/2f43032d5f001510c7eed059321ceeb76d07a606.1630419362.git.jani.nikula@intel.com

drivers/gpu/drm/drm_edid.c

@@ -49,6 +49,11 @@
 	(((edid)->version > (maj)) || \
 	 ((edid)->version == (maj) && (edid)->revision > (min)))
 
+static int oui(u8 first, u8 second, u8 third)
+{
+	return (first << 16) | (second << 8) | third;
+}
+
 #define EDID_EST_TIMINGS 16
 #define EDID_STD_TIMINGS 8
 #define EDID_DETAILED_TIMINGS 4
@@ -4113,32 +4118,24 @@ cea_db_offsets(const u8 *cea, int *start, int *end)
 
 static bool cea_db_is_hdmi_vsdb(const u8 *db)
 {
-	int hdmi_id;
-
 	if (cea_db_tag(db) != VENDOR_BLOCK)
 		return false;
 
 	if (cea_db_payload_len(db) < 5)
 		return false;
 
-	hdmi_id = db[1] | (db[2] << 8) | (db[3] << 16);
-
-	return hdmi_id == HDMI_IEEE_OUI;
+	return oui(db[3], db[2], db[1]) == HDMI_IEEE_OUI;
 }
 
 static bool cea_db_is_hdmi_forum_vsdb(const u8 *db)
 {
-	unsigned int oui;
-
 	if (cea_db_tag(db) != VENDOR_BLOCK)
 		return false;
 
 	if (cea_db_payload_len(db) < 7)
 		return false;
 
-	oui = db[3] << 16 | db[2] << 8 | db[1];
-
-	return oui == HDMI_FORUM_IEEE_OUI;
+	return oui(db[3], db[2], db[1]) == HDMI_FORUM_IEEE_OUI;
 }
 
 static bool cea_db_is_vcdb(const u8 *db)