mt7601u: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[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/20200901173603.GA2701@embeddedor

drivers/net/wireless/mediatek/mt7601u/dma.c

@@ -196,7 +196,7 @@ static void mt7601u_complete_rx(struct urb *urb)
 	default:
 		dev_err_ratelimited(dev->dev, "rx urb failed: %d\n",
 				    urb->status);
-		/* fall through */
+		fallthrough;
 	case 0:
 		break;
 	}
@@ -241,7 +241,7 @@ static void mt7601u_complete_tx(struct urb *urb)
 	default:
 		dev_err_ratelimited(dev->dev, "tx urb failed: %d\n",
 				    urb->status);
-		/* fall through */
+		fallthrough;
 	case 0:
 		break;
 	}

drivers/net/wireless/mediatek/mt7601u/mac.c

@@ -45,7 +45,7 @@ mt76_mac_process_tx_rate(struct ieee80211_tx_rate *txrate, u16 rate)
 		return;
 	case MT_PHY_TYPE_HT_GF:
 		txrate->flags |= IEEE80211_TX_RC_GREEN_FIELD;
-		/* fall through */
+		fallthrough;
 	case MT_PHY_TYPE_HT:
 		txrate->flags |= IEEE80211_TX_RC_MCS;
 		txrate->idx = idx;
@@ -419,7 +419,7 @@ mt76_mac_process_rate(struct ieee80211_rx_status *status, u16 rate)
 		return;
 	case MT_PHY_TYPE_HT_GF:
 		status->enc_flags |= RX_ENC_FLAG_HT_GF;
-		/* fall through */
+		fallthrough;
 	case MT_PHY_TYPE_HT:
 		status->encoding = RX_ENC_HT;
 		status->rate_idx = idx;

drivers/net/wireless/mediatek/mt7601u/phy.c

@@ -787,7 +787,7 @@ mt7601u_phy_rf_pa_mode_val(struct mt7601u_dev *dev, int phy_mode, int tx_rate)
 	switch (phy_mode) {
 	case MT_PHY_TYPE_OFDM:
 		tx_rate += 4;
-		/* fall through */
+		fallthrough;
 	case MT_PHY_TYPE_CCK:
 		reg = dev->rf_pa_mode[0];
 		break;