qcacld-3.0: dmgr: Replace fallthrough comment with attribute

-Wimplicit-fallthrough is being enabled by default. Some compilers
such as clang require the attribute instead of just a fallthrough comment.

Change-Id: I6ddf98a20bf0d5abb3088f8f231e9be8005f15e6
CRs-Fixed: 3217409

components/denylist_mgr/core/src/wlan_dlm_core.c

@@ -758,7 +758,6 @@ dlm_find_reject_type_string(enum dlm_reject_ap_type reject_ap_type)
 	CASE_RETURN_STRING(DRIVER_DENYLIST_TYPE);
 	CASE_RETURN_STRING(DRIVER_RSSI_REJECT_TYPE);
 	CASE_RETURN_STRING(DRIVER_MONITOR_TYPE);
-	/* fallthrough */
 	default:
 		return "REJECT_REASON_UNKNOWN";
 	}