qcacld-3.0: Fix array out-of-bound access in hdd_update_mac_config()

Fix array out-of-bound access in hdd_update_mac_config().

Change-Id: I8cd143c0db033ede780df8a93650917db4ede82d
CRs-Fixed: 2029437

core/hdd/src/wlan_hdd_cfg.c

@@ -5828,7 +5828,7 @@ QDF_STATUS hdd_update_mac_config(hdd_context_t *pHddCtx)
 	}
 	buffer = temp;
 	qdf_mem_copy(buffer, fw->data, fw->size);
-	buffer[fw->size + 1] = 0x0;
+	buffer[fw->size] = 0x0;
 
 	/* data format:
 	 * Intf0MacAddress=00AA00BB00CC