[build] Replace obsolete makerom.pl with quick script using Option::ROM

The only remaining useful function of makerom.pl is to correct the ROM
and PnP checksums; the PCI IDs are set at link time, and padding is
performed using padimg.pl.

Option::ROM already provides a facility for correcting the checksums,
so we may as well just use this instead.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/Makefile.housekeeping

@@ -614,15 +614,6 @@ TGT_LD_FLAGS	= $(foreach SYM,$(TGT_LD_PREFIX) $(TGT_LD_DRIVERS) obj_config,\
 		    -u $(SYM) --defsym check_$(SYM)=$(SYM) ) \
 		  $(patsubst %,--defsym %,$(TGT_LD_IDS))
 
-# Calculate makerom flags for the specific target
-# (e.g. "bin/dfe538--prism2_pci.zrom.tmp") and derive the variables:
-#
-# TGT_MAKEROM_FLAGS : target-specific flags for makerom (e.g.
-#		      "-p 0x1186,0x1300")
-#
-TGT_MAKEROM_FLAGS = $(strip $(MAKEROM_FLAGS_$(TGT_ROM_NAME)) \
-       $(if $(TGT_PCI_VENDOR),$(strip -p $(TGT_PCI_VENDOR),$(TGT_PCI_DEVICE))))
-
 # Calculate list of debugging versions of objects to be included in
 # the target.
 #
@@ -653,8 +644,6 @@ $(BIN)/%.info :
 	@$(ECHO)
 	@$(ECHO) 'LD target flags      : $(TGT_LD_FLAGS)'
 	@$(ECHO)
-	@$(ECHO) 'makerom target flags : $(TGT_MAKEROM_FLAGS)'
-	@$(ECHO)
 	@$(ECHO) 'Debugging objects    : $(DEBUG_OBJS)'
 	@$(ECHO) 'Replaced objects     : $(DEBUG_ORIG_OBJS)'
 
@@ -863,19 +852,6 @@ $(BIN)/etherboot.% : $(BIN)/ipxe.%
 
 endif # defined(BIN)
 
-###############################################################################
-#
-# Rules for finalising files.  TGT_MAKEROM_FLAGS is defined as part of
-# the automatic build system and varies by target; it includes the
-# "-p 0x1234,0x5678" string to set the PCI IDs.
-#
-FINALISE_rom	= $(MAKEROM) $(MAKEROM_FLAGS) $(TGT_MAKEROM_FLAGS) \
-		  -i$(IDENT) -s 0 $@
-
-# Some ROMs require specific flags to be passed to makerom.pl
-#
-MAKEROM_FLAGS_3c503 = -3
-
 ###############################################################################
 #
 # The compression utilities