crypto: arm64/sha - Add declarations for assembly variables

This patch adds declarations for variables only used by assembly
code to silence compiler warnings:

  CC [M]  arch/arm64/crypto/sha1-ce-glue.o
  AS [M]  arch/arm64/crypto/sha1-ce-core.o
  CC [M]  arch/arm64/crypto/sha2-ce-glue.o
  AS [M]  arch/arm64/crypto/sha2-ce-core.o
  CHECK   ../arch/arm64/crypto/sha1-ce-glue.c
  CHECK   ../arch/arm64/crypto/sha2-ce-glue.c
../arch/arm64/crypto/sha1-ce-glue.c:38:11: warning: symbol 'sha1_ce_offsetof_count' was not declared. Should it be static?
../arch/arm64/crypto/sha1-ce-glue.c:39:11: warning: symbol 'sha1_ce_offsetof_finalize' was not declared. Should it be static?
../arch/arm64/crypto/sha2-ce-glue.c:38:11: warning: symbol 'sha256_ce_offsetof_count' was not declared. Should it be static?
../arch/arm64/crypto/sha2-ce-glue.c:40:11: warning: symbol 'sha256_ce_offsetof_finalize' was not declared. Should it be static?

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>