drm/i915: Fix sprite_scaling_enabled for multiple sprites

We have more than one sprite, so a boolean simply won't cut it.
Turn sprite_scaling_enabled into a bitmask and track the state
of sprite scaler for each sprite independently.

Also don't re-enable LP watermarks until the sprite registers
have actually been written, and thus sprite scaling has really
been disabled.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 4e5a377..a7860ea 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -925,7 +925,7 @@
 
 	/* overlay */
 	struct intel_overlay *overlay;
-	bool sprite_scaling_enabled;
+	unsigned int sprite_scaling_enabled;
 
 	/* LVDS info */
 	int backlight_level;  /* restore backlight to this value */