drm/vc4: Fix memory leak during gpu reset.

__drm_atomic_helper_crtc_destroy_state does not free memory, it only
cleans it up. Fix this by calling the functions own destroy function.

Fixes: 6d6e5003 ("drm/vc4: Allocate the right amount of space for boot-time CRTC state.")
Cc: Eric Anholt <eric@anholt.net>
Cc: <stable@vger.kernel.org> # v4.6+
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190301125627.7285-2-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/vc4/vc4_crtc.c

@@ -1042,7 +1042,7 @@ static void
 vc4_crtc_reset(struct drm_crtc *crtc)
 {
 	if (crtc->state)
-		__drm_atomic_helper_crtc_destroy_state(crtc->state);
+		vc4_crtc_destroy_state(crtc->state);
 
 	crtc->state = kzalloc(sizeof(struct vc4_crtc_state), GFP_KERNEL);
 	if (crtc->state)