cxgb4/t4_hw: mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Addresses-Coverity-ID: 114777 ("Missing break in switch")
Addresses-Coverity-ID: 114778 ("Missing break in switch")
Addresses-Coverity-ID: 114779 ("Missing break in switch")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

@@ -7504,10 +7504,13 @@ int t4_alloc_vi(struct adapter *adap, unsigned int mbox, unsigned int port,
 		switch (nmac) {
 		case 5:
 			memcpy(mac + 24, c.nmac3, sizeof(c.nmac3));
+			/* Fall through */
 		case 4:
 			memcpy(mac + 18, c.nmac2, sizeof(c.nmac2));
+			/* Fall through */
 		case 3:
 			memcpy(mac + 12, c.nmac1, sizeof(c.nmac1));
+			/* Fall through */
 		case 2:
 			memcpy(mac + 6,  c.nmac0, sizeof(c.nmac0));
 		}