mpc85xx: disable kernel uImage generation

The previous workaround for the unsupported mkimage xz compression
leads to the TP-Link TL-WDR4900s simpleImage bootwrapper being gzip
compressed, which does not fit the kernel partition.

Removing the uImage gerneration works around this problem.

Signed-off-by: David Bauer <mail@david-bauer.net>

target/linux/mpc85xx/patches-5.4/900-powerpc-bootwrapper-disable-uImage-generation.patch

@@ -0,0 +1,42 @@
+From d43ab14605510d9d2bd257a8cd70f24ada4621b0 Mon Sep 17 00:00:00 2001
+From: David Bauer <mail@david-bauer.net>
+Date: Sat, 29 Feb 2020 14:27:04 +0100
+Subject: [PATCH] powerpc: bootwrapper: disable uImage generation
+
+Due to CONFIG_KERNEL_XZ symbol, the bootwrapper code tries to
+instruct the mkimage to use the xz compression, which isn't
+supported. This disables the uImage generation, as OpenWrt
+generates individual uImages for each board using it's own
+toolchain.
+
+Signed-off-by: David Bauer <mail@david-bauer.net>
+---
+ arch/powerpc/boot/Makefile | 9 ---------
+ 1 file changed, 9 deletions(-)
+
+--- a/arch/powerpc/boot/Makefile
++++ b/arch/powerpc/boot/Makefile
+@@ -268,7 +268,6 @@ image-$(CONFIG_PPC_CHRP)		+= zImage.chrp
+ image-$(CONFIG_PPC_EFIKA)		+= zImage.chrp
+ image-$(CONFIG_PPC_PMAC)		+= zImage.pmac
+ image-$(CONFIG_PPC_HOLLY)		+= dtbImage.holly
+-image-$(CONFIG_DEFAULT_UIMAGE)		+= uImage
+ image-$(CONFIG_EPAPR_BOOT)		+= zImage.epapr
+
+ #
+@@ -397,15 +396,6 @@ $(obj)/dtbImage.%: vmlinux $(wrapperbits
+ $(obj)/vmlinux.strip: vmlinux
+ 	$(STRIP) -s -R .comment $< -o $@
+
+-$(obj)/uImage: vmlinux $(wrapperbits) FORCE
+-	$(call if_changed,wrap,uboot)
+-
+-$(obj)/uImage.initrd.%: vmlinux $(obj)/dts/%.dtb $(wrapperbits) FORCE
+-	$(call if_changed,wrap,uboot-$*,,$(obj)/dts/$*.dtb,$(obj)/ramdisk.image.gz)
+-
+-$(obj)/uImage.%: vmlinux $(obj)/dts/%.dtb $(wrapperbits) FORCE
+-	$(call if_changed,wrap,uboot-$*,,$(obj)/dts/$*.dtb)
+-
+ $(obj)/cuImage.initrd.%: vmlinux $(obj)/dts/%.dtb $(wrapperbits) FORCE
+ 	$(call if_changed,wrap,cuboot-$*,,$(obj)/dts/$*.dtb,$(obj)/ramdisk.image.gz)
+