Build failed

Got this error on the linaro 4.9 aarch64 toolchain.

In file included from arch/arm64/crypto/sha1-ce-glue.c:15:0:
include/linux/cpufeature.h:47:33: warning: ‘cpu_feature_match_SHA1’ defined but not used [-Wunused-const-variable=]
error, forbidden warning: cpufeature.h:47
scripts/Makefile.build:257: recipe for target 'arch/arm64/crypto/sha1-ce-glue.o' failed
make[1]: *** [arch/arm64/crypto/sha1-ce-glue.o] Error 1
Makefile:946: recipe for target 'arch/arm64/crypto' failed
make: *** [arch/arm64/crypto] Error 2
make: *** Waiting for unfinished jobs....