drm/etnaviv: Fix a leak in submit_pin_objects()

If the mapping address is wrong then we have to release the reference to
it before returning -EINVAL.

Fixes: 088880ddc0 ("drm/etnaviv: implement softpin")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c

@@ -238,8 +238,10 @@ static int submit_pin_objects(struct etnaviv_gem_submit *submit)
 		}
 
 		if ((submit->flags & ETNA_SUBMIT_SOFTPIN) &&
-		     submit->bos[i].va != mapping->iova)
+		     submit->bos[i].va != mapping->iova) {
+			etnaviv_gem_mapping_unreference(mapping);
 			return -EINVAL;
+		}
 
 		atomic_inc(&etnaviv_obj->gpu_active);