Input: cypress_ps2 - fix trackpadi found in Dell XPS12

Avoid firmware glitch in Cypress PS/2 Trackpad firmware version 11
(as observed in Dell XPS12) which prevents driver from recognizing
the trackpad.

BugLink: http://launchpad.net/bugs/1103594



Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Cc: Dudley Du <dudl@cypress.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>