Fix RISCV64 Tumbleweed example build

Signed-off-by: Loic Devulder <ldevulder@suse.com>

Makefile

@@ -30,6 +30,11 @@ LDFLAGS+=-X "github.com/rancher/elemental-toolkit/internal/version.gitCommit=${G
 ifeq ($(PLATFORM),linux/riscv64)
 BASE_OS_IMAGE=registry.opensuse.org/opensuse/factory/riscv/images/opensuse/tumbleweed
 BASE_OS_VERSION=latest
+ifeq ($(FLAVOR),tumbleweed)
+OS_IMAGE=registry.opensuse.org/opensuse/factory/riscv/images/opensuse/tumbleweed
+ADD_REPO=https://download.opensuse.org/repositories/devel:/RISCV:/Factory:/Contrib:/StarFive:/VisionFive2/standard
+BUILD_OPTS=--build-arg OS_IMAGE=$(OS_IMAGE) --build-arg ADD_REPO=$(ADD_REPO)
+endif
 endif
 
 # default target
@@ -65,7 +70,7 @@ build-os: build
 			--build-arg TOOLKIT_REPO=$(TOOLKIT_REPO) \
 			--build-arg VERSION=$(VERSION) \
 			--build-arg REPO=$(REPO) -t $(REPO):$(VERSION) \
-			examples/$(FLAVOR)
+			$(BUILD_OPTS) examples/$(FLAVOR)
 
 .PHONY: push-os
 push-os: