roms: add 'make clean'

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/roms/Makefile b/roms/Makefile
index 7a228ae..b646060 100644
--- a/roms/Makefile
+++ b/roms/Makefile
@@ -75,3 +75,10 @@
 
 ipxe/src/config/local/%: config.ipxe.%
 	cp $< $@
+
+
+clean:
+	rm -rf seabios/.config seabios/out
+	$(MAKE) $(MAKEFLAGS) -C vgabios clean
+	rm -f vgabios/VGABIOS-lgpl-latest*
+	$(MAKE) $(MAKEFLAGS) -C ipxe/src veryclean