videomode: videomode_from_timing work

We currently have videomode_from_timing(), which takes one
display_timing entry from display_timings.

To make it easier to use display_timing without display_timings, this
patch renames videomode_from_timing() to videomode_from_timings(), and
adds a new videomode_from_timing() which just converts a given
display_timing to videomode.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Steffen Trumtrar <s.trumtrar@pengutronix.de>
diff --git a/drivers/video/of_videomode.c b/drivers/video/of_videomode.c
index 5b8066c..111c2d1 100644
--- a/drivers/video/of_videomode.c
+++ b/drivers/video/of_videomode.c
@@ -43,7 +43,7 @@
 	if (index == OF_USE_NATIVE_MODE)
 		index = disp->native_mode;
 
-	ret = videomode_from_timing(disp, vm, index);
+	ret = videomode_from_timings(disp, vm, index);
 	if (ret)
 		return ret;