cifs: set the port in sockaddr in a more clearly defined fashion

This patch should replace the patch I sent a couple of weeks ago to
set the port in cifs_convert_address.

Currently we set this in cifs_find_tcp_session, but that's more of a
side effect than anything. Add a new function called cifs_fill_sockaddr.
Have it call cifs_convert_address and then set the port.

This also allows us to skip passing in the port as a separate parm to
cifs_find_tcp_session.

Also, change cifs_convert_address take a struct sockaddr * rather than
void * to make it clearer how this function should be called.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>