[build] Add "allmroms" target

Signed-off-by: Bastian Blank <waldi@debian.org>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/Makefile.housekeeping

 
 # The "allXXXs" targets for each suffix
 #
-allall: allroms allpxes allisos alldsks
-allroms : all%s : $(foreach ROM,$(ROMS),$(BIN)/$(ROM).%)
+allall: allroms allmroms allpxes allisos alldsks
+allroms allmroms : all%s : $(foreach ROM,$(ROMS),$(BIN)/$(ROM).%)
 allpxes allisos alldsks : all%s : $(foreach DRIVER,$(DRIVERS),$(BIN)/$(DRIVER).%)
 
 # Alias for ipxe.%