fix kernel compile problem for arm64 (sonic-net#137)

- generate .config files for armhf, arm64, amd64 in turn.
- Compile the kernel with the corresponding environment variable.
- rely on updates to the sonic-slave-buster, see PR sonic-net#4639.

Co-authored-by: taocy <taocy2@centecnetworks.com>

Makefile

@@ -74,13 +74,13 @@ $(addprefix $(DEST)/, $(MAIN_TARGET)): $(DEST)/% :
 	debian/bin/gencontrol.py
 
 	# generate linux build file for amd64_none_amd64
-	# fakeroot make -f debian/rules.gen setup_armhf_none_armmp
-	# fakeroot make -f debian/rules.gen setup_arm64_none
-	fakeroot make -f debian/rules.gen setup_amd64_none_amd64
+	fakeroot make -f debian/rules.gen DEB_HOST_ARCH=armhf setup_armhf_none_armmp
+	fakeroot make -f debian/rules.gen DEB_HOST_ARCH=arm64 setup_arm64_none
+	fakeroot make -f debian/rules.gen DEB_HOST_ARCH=amd64 setup_amd64_none_amd64
 
 	# Applying patches and configuration changes
-	# git add debian/build/build_armhf_none_armmp/.config -f
-	# git add debian/build/build_arm64_none_arm64/.config -f
+	git add debian/build/build_armhf_none_armmp/.config -f
+	git add debian/build/build_arm64_none_arm64/.config -f
 	git add debian/build/build_amd64_none_amd64/.config -f
 	git add debian/config.defines.dump -f
 	git add debian/control -f
@@ -93,11 +93,11 @@ $(addprefix $(DEST)/, $(MAIN_TARGET)): $(DEST)/% :
 	stg import -s ../patch/series
 
 	# Building a custom kernel from Debian kernel source
-	DO_DOCS=False fakeroot make -f debian/rules -j $(shell nproc) binary-indep
+	ARCH=$(CONFIGURED_ARCH) DEB_HOST_ARCH=$(CONFIGURED_ARCH) DO_DOCS=False fakeroot make -f debian/rules -j $(shell nproc) binary-indep
 ifeq ($(CONFIGURED_ARCH), armhf)
-	fakeroot make -f debian/rules.gen -j $(shell nproc) binary-arch_$(CONFIGURED_ARCH)_none_armmp
+	ARCH=$(CONFIGURED_ARCH) DEB_HOST_ARCH=$(CONFIGURED_ARCH) fakeroot make -f debian/rules.gen -j $(shell nproc) binary-arch_$(CONFIGURED_ARCH)_none_armmp
 else
-	fakeroot make -f debian/rules.gen -j $(shell nproc) binary-arch_$(CONFIGURED_ARCH)_none
+	ARCH=$(CONFIGURED_ARCH) DEB_HOST_ARCH=$(CONFIGURED_ARCH) fakeroot make -f debian/rules.gen -j $(shell nproc) binary-arch_$(CONFIGURED_ARCH)_none
 endif
 	popd