smb: server: don't use delayed_work for post_recv_credits_work

smb: server: don't use delayed_work for post_recv_credits_work

If we are using a hardcoded delay of 0 there's no point in
using delayed_work it only adds confusion.

The client also uses a normal work_struct and now
it is easier to move it to the common smbdirect_socket.

Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Fixes: 0626e6641f6b ("cifsd: add server handler for central processing and tranport layers")
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>