drm/udl: Add register constants for video locks

Add register constants for the video lock. No functional changes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221006095355.23579-15-tzimmermann@suse.de

drivers/gpu/drm/udl/udl_modeset.c

@@ -41,12 +41,12 @@ static char *udl_set_register(char *buf, u8 reg, u8 val)
 
 static char *udl_vidreg_lock(char *buf)
 {
-	return udl_set_register(buf, 0xFF, 0x00);
+	return udl_set_register(buf, UDL_REG_VIDREG, UDL_VIDREG_LOCK);
 }
 
 static char *udl_vidreg_unlock(char *buf)
 {
-	return udl_set_register(buf, 0xFF, 0xFF);
+	return udl_set_register(buf, UDL_REG_VIDREG, UDL_VIDREG_UNLOCK);
 }
 
 static char *udl_set_blank_mode(char *buf, u8 mode)

drivers/gpu/drm/udl/udl_proto.h

@@ -31,4 +31,9 @@
 #define UDL_BLANKMODE_HSYNC_OFF		0x05 /* hsync off, blanked */
 #define UDL_BLANKMODE_POWERDOWN		0x07 /* powered off; requires modeset */
 
+/* Lock/unlock video registers */
+#define UDL_REG_VIDREG			0xff
+#define UDL_VIDREG_LOCK			0x00
+#define UDL_VIDREG_UNLOCK		0xff
+
 #endif