rawio/Makefile: add 'clean' target

Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Juan David Gonzalez Cobas <dcobas@cern.ch>

rawio/Makefile

 vmeio: vmeio.c
 	$(CC) -g -Wall -I../include $^ -o $@
+clean:
+	rm -rf vmeio
+
+.PHONY: clean