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/cm-bf548/video.c b/board/cm-bf548/video.c
index d43f5a1..c501697 100644
--- a/board/cm-bf548/video.c
+++ b/board/cm-bf548/video.c
@@ -225,6 +225,12 @@
 	return 0;
 }
 
+void video_stop(void)
+{
+	DisablePPI();
+	DisableDMA();
+}
+
 static void dma_bitblit(void *dst, fastimage_t *logo, int x, int y)
 {
 	if (dcache_status())