xtensa: add U-Boot image support (uImage).

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

arch/xtensa/boot/Makefile

@@ -22,7 +22,7 @@ subdir-y	:= lib
 # Subdirs for the boot loader(s)
 
 bootdir-$(CONFIG_XTENSA_PLATFORM_ISS)	 += boot-elf
-bootdir-$(CONFIG_XTENSA_PLATFORM_XT2000) += boot-redboot boot-elf
+bootdir-$(CONFIG_XTENSA_PLATFORM_XT2000) += boot-redboot boot-elf boot-uboot
 
 
 zImage Image: $(bootdir-y)
@@ -41,3 +41,4 @@ vmlinux.bin.gz: vmlinux.bin FORCE
 
 boot-elf: vmlinux.bin
 boot-redboot: vmlinux.bin.gz
+boot-uboot: vmlinux.bin.gz

arch/xtensa/boot/boot-uboot/Makefile

@@ -0,0 +1,14 @@
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License.  See the file "COPYING" in the main directory of this archive
+# for more details.
+#
+
+UIMAGE_LOADADDR = 0xd0001000
+UIMAGE_COMPRESSION = gzip
+
+$(obj)/../uImage: vmlinux.bin.gz FORCE
+	$(call if_changed,uimage)
+	$(Q)$(kecho) '  Kernel: $@ is ready'
+
+zImage: $(obj)/../uImage