iwlegacy: common: mark expected switch fall-throughs

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

Addresses-Coverity-ID: 201384 ("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/intel/iwlegacy/common.c

@@ -2695,6 +2695,7 @@ il_set_decrypted_flag(struct il_priv *il, struct ieee80211_hdr *hdr,
 		if ((decrypt_res & RX_RES_STATUS_DECRYPT_TYPE_MSK) ==
 		    RX_RES_STATUS_BAD_KEY_TTAK)
 			break;
+		/* fall through */
 
 	case RX_RES_STATUS_SEC_TYPE_WEP:
 		if ((decrypt_res & RX_RES_STATUS_DECRYPT_TYPE_MSK) ==
@@ -2704,6 +2705,7 @@ il_set_decrypted_flag(struct il_priv *il, struct ieee80211_hdr *hdr,
 			D_RX("Packet destroyed\n");
 			return -1;
 		}
+		/* fall through */
 	case RX_RES_STATUS_SEC_TYPE_CCMP:
 		if ((decrypt_res & RX_RES_STATUS_DECRYPT_TYPE_MSK) ==
 		    RX_RES_STATUS_DECRYPT_OK) {