video: simplefb: add rotation support

It introduces the way to rotate the screen for boards with rotated screen.

Signed-off-by: Takumi Sueda <puhitaku@gmail.com>
diff --git a/drivers/video/simplefb.c b/drivers/video/simplefb.c
index 2b0d883..235ec76 100644
--- a/drivers/video/simplefb.c
+++ b/drivers/video/simplefb.c
@@ -43,7 +43,11 @@
 
 	uc_priv->xsize = fdtdec_get_uint(blob, node, "width", 0);
 	uc_priv->ysize = fdtdec_get_uint(blob, node, "height", 0);
-	uc_priv->rot = 0;
+	uc_priv->rot = fdtdec_get_uint(blob, node, "rot", 0);
+	if (uc_priv->rot > 3) {
+		log_debug("%s: invalid rot\n", __func__);
+		return log_msg_ret("rot", -EINVAL);
+	}
 
 	format = fdt_getprop(blob, node, "format", NULL);
 	debug("%s: %dx%d@%s\n", __func__, uc_priv->xsize, uc_priv->ysize, format);