ARC: [build] Allow uncompressed uImage

The existing uImage target always generates gzip compressed image which
drags bootup for some very slow FPGA customer boards.

So introduce seperate make targets:uImage.{bin,gz} with uncompressed
being default. Also tie gz generation to CONFIG_KERNEL_GZIP, which a
platform can select in it's Kconfig if it wishes gz to be default.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/Makefile

@@ -102,10 +102,11 @@ boot		:= arch/arc/boot
 KBUILD_IMAGE	:= bootpImage
 
 all:	$(KBUILD_IMAGE)
-
 bootpImage: vmlinux
 
-uImage: vmlinux
+boot_targets += uImage uImage.bin uImage.gz
+
+$(boot_targets): vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
 
 %.dtb %.dtb.S %.dtb.o: scripts

arch/arc/boot/Makefile

@@ -11,7 +11,12 @@ LINUX_START_TEXT = $$(readelf -h vmlinux | \
 
 UIMAGE_LOADADDR    = $(CONFIG_LINUX_LINK_BASE)
 UIMAGE_ENTRYADDR   = $(LINUX_START_TEXT)
-UIMAGE_COMPRESSION = gzip
+
+suffix-y := bin
+suffix-$(CONFIG_KERNEL_GZIP)	:= gz
+
+targets += uImage uImage.bin uImage.gz
+extra-y += vmlinux.bin vmlinux.bin.gz
 
 $(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)
@@ -19,6 +24,12 @@ $(obj)/vmlinux.bin: vmlinux FORCE
 $(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
 	$(call if_changed,gzip)
 
-$(obj)/uImage: $(obj)/vmlinux.bin.gz FORCE
-	$(call if_changed,uimage)
+$(obj)/uImage.bin: $(obj)/vmlinux.bin FORCE
+	$(call if_changed,uimage,none)
+
+$(obj)/uImage.gz: $(obj)/vmlinux.bin.gz FORCE
+	$(call if_changed,uimage,gzip)
 
+$(obj)/uImage: $(obj)/uImage.$(suffix-y)
+	@ln -sf $(notdir $<) $@
+	@echo '  Image $@ is ready'