smb: client: Avoid leaking sensitive data to the heap in connect.c

TCP_Server_Info contains a preauth_sha_hash[] and a cryptkey[] array
that might contain sensitive data. Thus free its memory with
kfree_sensitive() to avoid that we are leaking this information to
the heap.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>