OMAP: DSS2: OMAPFB: Add some locking debug checks

Trigger WARN_ON() messages from various places in the code in case the
memory region is not currently locked.

Signed-off-by: Ville Syrjälä <ville.syrjala@nokia.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>
diff --git a/drivers/video/omap2/omapfb/omapfb-ioctl.c b/drivers/video/omap2/omapfb/omapfb-ioctl.c
index 7975a99..d1f56d3 100644
--- a/drivers/video/omap2/omapfb/omapfb-ioctl.c
+++ b/drivers/video/omap2/omapfb/omapfb-ioctl.c
@@ -222,6 +222,7 @@
 	rg = ofbi->region;
 
 	down_write_nested(&rg->lock, rg->id);
+	atomic_inc(&rg->lock_count);
 
 	if (atomic_read(&rg->map_count)) {
 		r = -EBUSY;
@@ -252,6 +253,7 @@
 	}
 
  out:
+	atomic_dec(&rg->lock_count);
 	up_write(&rg->lock);
 
 	return r;