lib/sha1.c: quiet sparse noise about symbol not declared

Include <linux/cryptohash.h> to pickup the declarations for sha_transform
and sha_init to quite the sparse noise:

  warning: symbol 'sha_transform' was not declared. Should it be static?
  warning: symbol 'sha_init' was not declared. Should it be static?

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Mandeep Singh Baines <msb@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>