[PATCH] net: smc911x: Mark expected switch fall-through

["Gustavo A. R. Silva" <gustavo@embeddedor.com>]

Mark switch cases where we are expecting to fall through.

This patch fixes the following warning (Building: arm):

drivers/net/ethernet/smsc/smc911x.c: In function ‘smc911x_phy_detect’:
drivers/net/ethernet/smsc/smc911x.c:677:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
    if (cfg & HW_CFG_EXT_PHY_DET_) {
       ^
drivers/net/ethernet/smsc/smc911x.c:715:3: note: here
   default:
   ^~~~~~~

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/net/ethernet/smsc/smc911x.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/smsc/smc911x.c b/drivers/net/ethernet/smsc/smc911x.c
index bd14803545de..8d88e4083456 100644
--- a/drivers/net/ethernet/smsc/smc911x.c
+++ b/drivers/net/ethernet/smsc/smc911x.c
@@ -712,6 +712,7 @@ static void smc911x_phy_detect(struct net_device *dev)
 					/* Found an external PHY */
 					break;
 			}
+			/* Else, fall through */
 		default:
 			/* Internal media only */
 			SMC_GET_PHY_ID1(lp, 1, id1);
-- 
2.22.0