RDMA/siw: Use crypto_shash_digest() in siw_qp_prepare_tx()

Simplify siw_qp_prepare_tx() by using crypto_shash_digest() instead of
an init+update+final sequence.  This should also improve performance.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20231029045839.154071-1-ebiggers@kernel.org


Acked-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>