disable kernel build waring

hc

2024-05-10 093a6c67005148ae32a5c9e4553491b9f5c2457b

 kernel/arch/mips/bcm63xx/boards/Makefile
..
..
@@ -1 +1,2 @@
1
+# SPDX-License-Identifier: GPL-2.0-only
1
2
 obj-$(CONFIG_BOARD_BCM963XX)		+= board_bcm963xx.o