ksmbd: don't need 8byte alignment for request length in ksmbd_check_message

When validating request length in ksmbd_check_message, 8byte alignment
is not needed for compound request. It can cause wrong validation
of request length.

Fixes: e2f34481

 ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org # v5.15
Acked-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>