*-legacy-flash: Deduplicate generation of "top" ROM

Move Makefile target for the "top" ROM to targets/legacy_flash.mk.

Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>

Author: JonathonHall-Purism

boards/UNTESTED_t430-legacy-flash/UNTESTED_t430-legacy-flash.config

@@ -32,19 +32,4 @@ export CONFIG_FLASHROM_OPTIONS="--force --noverify-all -p internal --ifd --image
 
 CONFIG_LEGACY_FLASH=y
 
-# This board is "special" in that we need a 4MB top SPI flashable ROM.
-# This is enough to allow the board to boot into a minimal Heads and read the full Legacy
-# ROM from an external USB media.
-# 
-# No tools outside of flashrom are provided here as you can see per activated modules above.
-# Everything Heads is now delegated to the Legacy ROM to be flashed
-# from xx30-flash ROMs. 
-#
-# Instructions to mount USB thumb drive and flash legacy 12Mb image will be given on screen
-# per CONFIG_BOOTSCRIPT script above.
-#
-# Below, we just move produced ROM with a name appended with -top.rom for clarity.
-all: $(board_build)/heads-$(BOARD)-$(HEADS_GIT_VERSION)-top.rom
-$(board_build)/heads-$(BOARD)-$(HEADS_GIT_VERSION)-top.rom: $(board_build)/$(CB_OUTPUT_FILE)
-	$(call do,MV 4MB top ROM,$@, mv $< $@)
-	@sha256sum $@
+BOARD_TARGETS := legacy_flash

boards/x230-legacy-flash/x230-legacy-flash.config

@@ -33,19 +33,4 @@ export CONFIG_FLASHROM_OPTIONS="--force --noverify-all -p internal --ifd --image
 
 CONFIG_LEGACY_FLASH=y
 
-# This board is "special" in that we need a 4MB top SPI flashable ROM.
-# This is enough to allow the board to boot into a minimal Heads and read the full Legacy
-# ROM from an external USB media.
-# 
-# No tools outside of flashrom are provided here as you can see per activated modules above.
-# Everything Heads is now delegated to the Legacy ROM to be flashed
-# from xx30-flash ROMs. 
-#
-# Instructions to mount USB thumb drive and flash legacy 12Mb image will be given on screen
-# per CONFIG_BOOTSCRIPT script above.
-#
-# Below, we just move produced ROM with a name appended with -top.rom for clarity.
-all: $(board_build)/heads-$(BOARD)-$(HEADS_GIT_VERSION)-top.rom
-$(board_build)/heads-$(BOARD)-$(HEADS_GIT_VERSION)-top.rom: $(board_build)/$(CB_OUTPUT_FILE)
-	$(call do,MV 4MB top ROM,$@, mv $< $@)
-	@sha256sum $@
+BOARD_TARGETS := legacy_flash

targets/legacy_flash.mk

@@ -0,0 +1,16 @@
+# legacy-flash boards are "special" in that we need a 4MB top SPI flashable ROM.
+# This is enough to allow the board to boot into a minimal Heads and read the full Legacy
+# ROM from an external USB media.
+#
+# No tools outside of flashrom are provided here as you can see per activated modules above.
+# Everything Heads is now delegated to the Legacy ROM to be flashed
+# from xx30-flash ROMs.
+#
+# Instructions to mount USB thumb drive and flash legacy 12Mb image will be given on screen
+# per CONFIG_BOOTSCRIPT script above.
+#
+# Below, we just move produced ROM with a name appended with -top.rom for clarity.
+all: $(board_build)/heads-$(BOARD)-$(HEADS_GIT_VERSION)-top.rom
+$(board_build)/heads-$(BOARD)-$(HEADS_GIT_VERSION)-top.rom: $(board_build)/$(CB_OUTPUT_FILE)
+	$(call do,MV 4MB top ROM,$@, mv $< $@)
+	@sha256sum $@