kernel: use buildroot instead of radxa bsp to prepare the source code

Signed-off-by: Ruixi Zhou <[email protected]>

Author: zhouruixi

board/radxa/zero3/local.mk board/common/local.mkboard/radxa/zero3/local.mk renamed to board/common/local.mk

@@ -1,6 +1,3 @@
-LINUX_OVERRIDE_SRCDIR=$(BUILD_DIR)/radxa-bsp-main/.src/linux
-LINUX_CFLAGS = "-Wno-enum-int-mismatch"
-
 define BUSYBOX_APPLY_CUSTOM_PATCHES
     $(APPLY_PATCHES) $(@D) $(BR2_EXTERNAL_OPENIPC_SBC_GS_PATH)/package/busybox \*.patch
 endef