ksmbd: smbd: simplify tracking pending packets

Because we don't have to tracking pending packets
by dividing these into packets with payload and
packets without payload, merge the tracking code.

Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>