roms/Makefile: Add qboot to .PHONY list

Adding qboot to the .PHONY directive will allow a
make -C roms qboot invocation to work as expected

Signed-off-by: Bruce Rogers <brogers@suse.com>
Message-id: 20201020152512.837769-1-brogers@suse.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

roms/Makefile

@@ -102,7 +102,7 @@ build-seabios-config-%: config.%
 		OUT=$(CURDIR)/seabios/builds/$*/ all
 
 
-.PHONY: sgabios skiboot
+.PHONY: sgabios skiboot qboot
 sgabios:
 	$(MAKE) -C sgabios
 	cp sgabios/sgabios.bin ../pc-bios