drm/radeon/kms: switch to condition waiting for reclocking

We tried to implement interruptible waiting with timeout (it was broken
anyway) which was not a good idea as explained by Andrew. It's possible
to avoid using additional variable but actually it inroduces using more
complex in-kernel tools. So simply add one variable for condition.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/rs600.c b/drivers/gpu/drm/radeon/rs600.c
index 47f046b..ac7c27a 100644
--- a/drivers/gpu/drm/radeon/rs600.c
+++ b/drivers/gpu/drm/radeon/rs600.c
@@ -392,10 +392,12 @@
 		/* Vertical blank interrupts */
 		if (G_007EDC_LB_D1_VBLANK_INTERRUPT(r500_disp_int)) {
 			drm_handle_vblank(rdev->ddev, 0);
+			rdev->pm.vblank_sync = true;
 			wake_up(&rdev->irq.vblank_queue);
 		}
 		if (G_007EDC_LB_D2_VBLANK_INTERRUPT(r500_disp_int)) {
 			drm_handle_vblank(rdev->ddev, 1);
+			rdev->pm.vblank_sync = true;
 			wake_up(&rdev->irq.vblank_queue);
 		}
 		if (G_007EDC_DC_HOT_PLUG_DETECT1_INTERRUPT(r500_disp_int)) {