[build] Provide %.fd0 build targets only for pcbios

Originally-fixed-by: Piotr Jaroszyński <p.jaroszynski@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/Makefile.housekeeping

 # ROMS), and (b) the linker is so fast that it probably wouldn't make
 # much difference to the overall build time.
 
+# Add NON_AUTO_MEDIA to the media list, so that they show up in the
+# output of "make"
+#
+MEDIA		+= $(NON_AUTO_MEDIA)
+
 media :
 	@$(ECHO) $(MEDIA)
 

src/arch/i386/Makefile

 #
 MAKEDEPS	+= arch/i386/Makefile.$(PLATFORM)
 include arch/i386/Makefile.$(PLATFORM)
-
-# Some suffixes (e.g. %.fd0) are generated directly from other
-# finished files (e.g. %.dsk), rather than having their own prefix.
-
-# rule to write disk images to /dev/fd0
-NON_AUTO_MEDIA	+= fd0
-%fd0 : %dsk
-	$(QM)$(ECHO) "  [DD] $@"
-	$(Q)dd if=$< bs=512 conv=sync of=/dev/fd0
-	$(Q)sync
-
-# Add NON_AUTO_MEDIA to the media list, so that they show up in the
-# output of "make"
-#
-MEDIA		+= $(NON_AUTO_MEDIA)

src/arch/i386/Makefile.pcbios

 	$(QM)$(ECHO) "  [GENSDSK] $@"
 	$(Q)bash util/gensdsk $@ $<
 
+# rule to write disk images to /dev/fd0
+NON_AUTO_MEDIA	+= fd0
+%fd0 : %dsk
+	$(QM)$(ECHO) "  [DD] $@"
+	$(Q)dd if=$< bs=512 conv=sync of=/dev/fd0
+	$(Q)sync
+
 # Special target for building Master Boot Record binary
 $(BIN)/mbr.bin : $(BIN)/mbr.o
 	$(QM)$(ECHO) "  [OBJCOPY] $@"