crypto: hisilicon/sec - add some comments for soft fallback

crypto: hisilicon/sec - add some comments for soft fallback

[ Upstream commit e764d81d58070e66e61fb1b972c81eb9d2ea971e ]

Modify the print of information that might lead to user misunderstanding.
Currently only XTS mode need the fallback tfm when using 192bit key.
Others algs not need soft fallback tfm. So others algs can return
directly.

Signed-off-by: Kai Ye <yekai13@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Stable-dep-of: fd337f852b26 ("crypto: hisilicon/sec2 - fix for aead icv error")
Signed-off-by: Sasha Levin <sashal@kernel.org>