virtio_ring: sparse warning fixup

virtio_store_mb was built with split ring in mind so it accepts
__virtio16 arguments. Packed ring uses __le16 values, so sparse
complains.  It's just a store with some barriers so let's convert it to
a macro, we don't loose too much type safety by doing that.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>

include/linux/virtio_ring.h

@@ -46,16 +46,15 @@ static inline void virtio_wmb(bool weak_barriers)
 		dma_wmb();
 }
 
-static inline void virtio_store_mb(bool weak_barriers,
-				   __virtio16 *p, __virtio16 v)
-{
-	if (weak_barriers) {
-		virt_store_mb(*p, v);
-	} else {
-		WRITE_ONCE(*p, v);
-		mb();
-	}
-}
+#define virtio_store_mb(weak_barriers, p, v) \
+do { \
+	if (weak_barriers) { \
+		virt_store_mb(*p, v); \
+	} else { \
+		WRITE_ONCE(*p, v); \
+		mb(); \
+	} \
+} while (0) \
 
 struct virtio_device;
 struct virtqueue;