smb: client: port and use the wait_for_credits logic used by server

smb: client: port and use the wait_for_credits logic used by server

This simplifies the logic and prepares the use of
smbdirect_send_batch in order to make sure
all messages in a multi fragment send are grouped
together.

We'll add the smbdirect_send_batch processin
in a later patch.

Cc: <stable@vger.kernel.org> # 6.18.x
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>