intelfb: add vsync interrupt support

[05/05] intelfb: Honor FB_ACTIVATE_VBL for display panning

Extends the intelfb_vsync struct to store panning offset. The interrupt service routine uses the stored panning offset if a pan is requested for the vsync. intelfbhw_disable_irq also pans the display if there is a pending request.

Signed-off-by: Eric Hustvedt <ehustvedt@cecropia.com>
diff --git a/drivers/video/intelfb/intelfbdrv.c b/drivers/video/intelfb/intelfbdrv.c
index 08f8241..9e93f82 100644
--- a/drivers/video/intelfb/intelfbdrv.c
+++ b/drivers/video/intelfb/intelfbdrv.c
@@ -900,6 +900,8 @@
 	init_waitqueue_head(&dinfo->vsync.wait);
 	spin_lock_init(&dinfo->int_lock);
 	dinfo->irq_flags = 0;
+	dinfo->vsync.pan_display = 0;
+	dinfo->vsync.pan_offset = 0;
 
 	return 0;