crypto: drop mask=CRYPTO_ALG_ASYNC from 'cipher' tfm allocations

'cipher' algorithms (single block ciphers) are always synchronous, so
passing CRYPTO_ALG_ASYNC in the mask to crypto_alloc_cipher() has no
effect.  Many users therefore already don't pass it, but some still do.
This inconsistency can cause confusion, especially since the way the
'mask' argument works is somewhat counterintuitive.

Thus, just remove the unneeded CRYPTO_ALG_ASYNC flags.

This patch shouldn't change any actual behavior.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>