x86: move defconfig files for i386 and x86_64 to x86

With some small changes to kconfig makefile we can now
locate the defconfig files for i386 and x86_64 in
the configs/ subdirectory under x86.
make ARCH=i386 defconfig and make defconfig
works as expected also after this change.
But arch maintainers shall now update a defconfig file in
the configs/ directory.
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

arch/x86/Makefile

 # Unified Makefile for i386 and x86_64
 
-# No need to remake these files
+# select defconfig based on actual architecture
+KBUILD_DEFCONFIG := $(ARCH)_defconfig
+
+# # No need to remake these files
 $(srctree)/arch/x86/Makefile%: ;
 
 ifeq ($(ARCH),i386)

scripts/kconfig/Makefile

@@ -60,12 +60,12 @@ defconfig: $(obj)/conf
 ifeq ($(KBUILD_DEFCONFIG),)
 	$< -d arch/$(ARCH)/Kconfig
 else
-	@echo *** Default configuration is based on '$(KBUILD_DEFCONFIG)'
-	$(Q)$< -D arch/$(ARCH)/configs/$(KBUILD_DEFCONFIG) arch/$(ARCH)/Kconfig
+	@echo "*** Default configuration is based on '$(KBUILD_DEFCONFIG)'"
+	$(Q)$< -D arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG) arch/$(ARCH)/Kconfig
 endif
 
 %_defconfig: $(obj)/conf
-	$(Q)$< -D arch/$(ARCH)/configs/$@ arch/$(ARCH)/Kconfig
+	$(Q)$< -D arch/$(SRCARCH)/configs/$@ arch/$(ARCH)/Kconfig
 
 # Help text used by make help
 help: