PPC32: don't use call descend in boot Makefiles

arch/ppc/Makefile

@@ -55,19 +55,21 @@ drivers-$(CONFIG_8xx)		+= arch/ppc/8xx_io/
 drivers-$(CONFIG_4xx)		+= arch/ppc/4xx_io/
 drivers-$(CONFIG_8260)		+= arch/ppc/8260_io/
 
-makeboot = $(call descend,arch/ppc/boot,$(1))
+makeboot =$(Q)$(MAKE) -f scripts/Makefile.build obj=arch/ppc/boot $(1)
 
 BOOT_TARGETS = zImage zImage.initrd znetboot znetboot.initrd pImage vmlinux.sm
 
 .PHONY: $(BOOT_TARGETS) clean archclean archmrproper
 
+all: zImage
+
 AFLAGS_vmlinux.lds.o	:= -Upowerpc
 
 # All the instructions talk about "make bzImage".
 bzImage: zImage
 
 $(BOOT_TARGETS): vmlinux
-	+@$(call makeboot,$@)
+	@$(call makeboot,$@)
 
 %_config: arch/ppc/configs/%_defconfig
 	rm -f .config arch/ppc/defconfig

arch/ppc/boot/Makefile

@@ -42,4 +42,4 @@ host-progs			:= $(addprefix utils/,$(tools-y))
 $(BOOT_TARGETS): $(bootdir-y)
 
 $(bootdir-y): $(addprefix $(obj)/,$(subdir-y))
-	+$(call descend,$(obj)/$@,$(MAKECMDGOALS))
+	$(Q)$(MAKE) -f scripts/Makefile.build obj=$(obj)/$@ $(MAKECMDGOALS)