Blackfin: shutdown video DMA when booting Linux

In case there is no frame buffer driver present in Linux to hand over the
PPI LCD DMA upon boot, the DMA initiated by u-boot to display the splash
screen runs unattended.  Therefore always stop the video driver in u-boot
before starting Linux.  If people don't want this behavior, then they can
simply stub out the video_stop() function in their board video driver.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/board/bf533-stamp/video.c b/board/bf533-stamp/video.c
index 939bd35..75b8adc 100644
--- a/board/bf533-stamp/video.c
+++ b/board/bf533-stamp/video.c
@@ -150,6 +150,12 @@
 	bfin_write_PPI_CONTROL(0x0083);
 }
 
+void video_stop(void)
+{
+	bfin_write_PPI_CONTROL(0);
+	bfin_write_DMA0_CONFIG(0);
+}
+
 int drv_video_init(void)
 {
 	struct stdio_dev videodev;