tty: fix warning in synclink driver

During builds I see the following warning -

  CC [M]  drivers/char/pcmcia/synclink_cs.o
drivers/char/pcmcia/synclink_cs.c:2194: warning: ‘mgslpc_get_icount’ defined but not used

The function is a callback meant to be assigned to get_icount (added during 0587102c).
Fix accordingly.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>