rtl8xxxu: Mark expected switch fall-throughs

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

Addresses-Coverity-ID: 1357355 ("Missing break in switch")
Addresses-Coverity-ID: 1357378 ("Missing break in switch")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c

@@ -1153,6 +1153,7 @@ void rtl8xxxu_gen1_config_channel(struct ieee80211_hw *hw)
 	switch (hw->conf.chandef.width) {
 	case NL80211_CHAN_WIDTH_20_NOHT:
 		ht = false;
+		/* fall through */
 	case NL80211_CHAN_WIDTH_20:
 		opmode |= BW_OPMODE_20MHZ;
 		rtl8xxxu_write8(priv, REG_BW_OPMODE, opmode);
@@ -1280,6 +1281,7 @@ void rtl8xxxu_gen2_config_channel(struct ieee80211_hw *hw)
 	switch (hw->conf.chandef.width) {
 	case NL80211_CHAN_WIDTH_20_NOHT:
 		ht = false;
+		/* fall through */
 	case NL80211_CHAN_WIDTH_20:
 		rf_mode_bw |= WMAC_TRXPTCL_CTL_BW_20;
 		subchannel = 0;
@@ -1748,9 +1750,11 @@ static int rtl8xxxu_identify_chip(struct rtl8xxxu_priv *priv)
 		case 3:
 			priv->ep_tx_low_queue = 1;
 			priv->ep_tx_count++;
+			/* fall through */
 		case 2:
 			priv->ep_tx_normal_queue = 1;
 			priv->ep_tx_count++;
+			/* fall through */
 		case 1:
 			priv->ep_tx_high_queue = 1;
 			priv->ep_tx_count++;