rtlwifi: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1].

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-throughSigned-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200821061807.GA8412@embeddedor

drivers/net/wireless/realtek/rtlwifi/base.c

@@ -2443,7 +2443,7 @@ static struct sk_buff *rtl_make_smps_action(struct ieee80211_hw *hw,
 	case IEEE80211_SMPS_AUTOMATIC:/* 0 */
 	case IEEE80211_SMPS_NUM_MODES:/* 4 */
 		WARN_ON(1);
-	/* fall through */
+		fallthrough;
 	case IEEE80211_SMPS_OFF:/* 1 */ /*MIMO_PS_NOLIMIT*/
 		action_frame->u.action.u.ht_smps.smps_control =
 				WLAN_HT_SMPS_CONTROL_DISABLED;/* 0 */

drivers/net/wireless/realtek/rtlwifi/core.c

@@ -227,7 +227,7 @@ static int rtl_op_add_interface(struct ieee80211_hw *hw,
 	switch (ieee80211_vif_type_p2p(vif)) {
 	case NL80211_IFTYPE_P2P_CLIENT:
 		mac->p2p = P2P_ROLE_CLIENT;
-		/*fall through*/
+		fallthrough;
 	case NL80211_IFTYPE_STATION:
 		if (mac->beacon_enabled == 1) {
 			rtl_dbg(rtlpriv, COMP_MAC80211, DBG_LOUD,
@@ -254,7 +254,7 @@ static int rtl_op_add_interface(struct ieee80211_hw *hw,
 		break;
 	case NL80211_IFTYPE_P2P_GO:
 		mac->p2p = P2P_ROLE_GO;
-		/*fall through*/
+		fallthrough;
 	case NL80211_IFTYPE_AP:
 		rtl_dbg(rtlpriv, COMP_MAC80211, DBG_LOUD,
 			"NL80211_IFTYPE_AP\n");

drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c

@@ -370,7 +370,7 @@ static void _rtl8812ae_phy_set_rfe_reg_24g(struct ieee80211_hw *hw)
 			rtl_set_bbreg(hw, RB_RFE_INV, BMASKRFEINV, 0x000);
 			break;
 		}
-		/* fall through */
+		fallthrough;
 	case 0:
 	case 2:
 	default: