crypto: add crypto_[un]register_shashes for [un]registering multiple … …shash entries at once 1

Add crypto_[un]register_shashes() to allow simplifying init/exit code of shash
crypto modules that register multiple algorithms.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>

https://github.com/neobuddy89/hammerhead/commit/1922d79b313f52ced0e3dd8eb09861b9c97cc386#diff-0