nvme-tcp: use crc32c() and skb_copy_and_crc32c_datagram_iter()

nvme-tcp: use crc32c() and skb_copy_and_crc32c_datagram_iter()

Now that the crc32c() library function directly takes advantage of
architecture-specific optimizations and there also now exists a function
skb_copy_and_crc32c_datagram_iter(), it is unnecessary to go through the
crypto_ahash API.  Just use those functions.  This is much simpler, and
it also improves performance due to eliminating the crypto API overhead.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://patch.msgid.link/20250519175012.36581-10-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>