ARM_ATAG_DTB_COMPAT fails on fdt_ro.c compiling

I have seen this error on mainline for a couple days when
ARM_ATAG_DTB_COMPAT is enabled.

  CC      arch/arm/boot/compressed/fdt_ro.o
arch/arm/boot/compressed/fdt_ro.c: In function ?fdt_path_offset?:
arch/arm/boot/compressed/fdt_ro.c:172:3: error: implicit declaration of function ?fdt_get_alias_namelen? [-Werror=implicit-function-declaration]
arch/arm/boot/compressed/fdt_ro.c:172:5: warning: assignment makes pointer from integer without a cast [enabled by default]
arch/arm/boot/compressed/fdt_ro.c: At top level:
arch/arm/boot/compressed/fdt_ro.c:340:13: error: conflicting types for ?fdt_get_alias_namelen?
arch/arm/boot/compressed/fdt_ro.c:172:7: note: previous implicit declaration of ?fdt_get_alias_namelen? was here
cc1: some warnings being treated as errors

Shawn