make: add make task to generate Renesas device wrappers

Signed-off-by: deadprogram <ron@hybridgroup.com>

Makefile

@@ -232,6 +232,10 @@ gen-device-rp: build/gen-device-svd
 	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/RaspberryPi lib/cmsis-svd/data/RaspberryPi/ src/device/rp/
 	GO111MODULE=off $(GO) fmt ./src/device/rp
 
+gen-device-renesas: build/gen-device-svd
+	./build/gen-device-svd -source=https://github.com/tinygo-org/renesas-svd lib/renesas-svd/ src/device/renesas/
+	GO111MODULE=off $(GO) fmt ./src/device/renesas
+
 # Get LLVM sources.
 $(LLVM_PROJECTDIR)/llvm:
 	git clone -b xtensa_release_15.x --depth=1 https://github.com/espressif/llvm-project $(LLVM_PROJECTDIR)