kernel: copy only *.ko for debug info

Previous commits installed non-elf files into /lib/modules/$VER/.
COLLECT_KERNEL_DEBUG tries to strip all files and these two files
break the build.
Fix it by copying only kernel modules for debug info collection.

Fixes: e1d8e57 ("kernel: include modinfo for built-in modules")
Fixes: 29f6da4 ("kernel: include built-in module list")
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>

include/kernel-build.mk

@@ -63,7 +63,7 @@ ifdef CONFIG_COLLECT_KERNEL_DEBUG
 	mkdir -p $(KERNEL_BUILD_DIR)/debug/modules
 	$(CP) $(LINUX_DIR)/vmlinux $(KERNEL_BUILD_DIR)/debug/
 	-$(CP) \
-		$(STAGING_DIR_ROOT)/lib/modules/$(LINUX_VERSION)/* \
+		$(STAGING_DIR_ROOT)/lib/modules/$(LINUX_VERSION)/*.ko \
 		$(KERNEL_BUILD_DIR)/debug/modules/
 	$(FIND) $(KERNEL_BUILD_DIR)/debug -type f | $(XARGS) $(KERNEL_CROSS)strip --only-keep-debug
 	$(TAR) c -C $(KERNEL_BUILD_DIR) debug \