video: Add an option to skip video initialization

This patch adds an option to skip the video initialization on for all
video drivers. This is needed for the CPCI750 which can be built as
CPCI host and adapter/target board. And the adapter board can't
access the video cards located on the CompactPCI bus.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Anatolij Gustschin <agust@denx.de>

Rebased against simplifying patch.
Signed-off-by: Wolfgang Denk <wd@denx.de>

drivers/video/cfb_console.c

@@ -1330,11 +1330,26 @@ static int video_init (void)
 
 /*****************************************************************************/
 
+/*
+ * Implement a weak default function for boards that optionally
+ * need to skip the video initialization.
+ */
+int __board_video_skip(void)
+{
+	/* As default, don't skip test */
+	return 0;
+}
+int board_video_skip(void) __attribute__((weak, alias("__board_video_skip")));
+
 int drv_video_init (void)
 {
 	int skip_dev_init;
 	device_t console_dev;
 
+	/* Check if video initialization should be skipped */
+	if (board_video_skip())
+		return 0;
+
 	/* Init video chip - returns with framebuffer cleared */
 	skip_dev_init = (video_init () == -1);