rt2x00: rt2800lib: mark expected switch fall-throughs

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

Addresses-Coverity-ID: 145198 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ralink/rt2x00/rt2800lib.c

@@ -2482,6 +2482,7 @@ static void rt2800_config_channel_rf3052(struct rt2x00_dev *rt2x00dev,
 		switch (rt2x00dev->default_ant.tx_chain_num) {
 		case 1:
 			rt2x00_set_field8(&rfcsr, RFCSR1_TX1_PD, 1);
+			/* fall through */
 		case 2:
 			rt2x00_set_field8(&rfcsr, RFCSR1_TX2_PD, 1);
 			break;
@@ -2490,6 +2491,7 @@ static void rt2800_config_channel_rf3052(struct rt2x00_dev *rt2x00dev,
 		switch (rt2x00dev->default_ant.rx_chain_num) {
 		case 1:
 			rt2x00_set_field8(&rfcsr, RFCSR1_RX1_PD, 1);
+			/* fall through */
 		case 2:
 			rt2x00_set_field8(&rfcsr, RFCSR1_RX2_PD, 1);
 			break;
@@ -9457,8 +9459,10 @@ static int rt2800_probe_hw_mode(struct rt2x00_dev *rt2x00dev)
 	switch (rx_chains) {
 	case 3:
 		spec->ht.mcs.rx_mask[2] = 0xff;
+		/* fall through */
 	case 2:
 		spec->ht.mcs.rx_mask[1] = 0xff;
+		/* fall through */
 	case 1:
 		spec->ht.mcs.rx_mask[0] = 0xff;
 		spec->ht.mcs.rx_mask[4] = 0x1; /* MCS32 */