Input: cyttsp - remove useless checks in cyttsp_probe()

This fixes reference-before-check problem; there is no reason to check
if caller passed NULL dev or bus_ops as it is done only by bus-specific
drivers which already do the right thing.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>