mfd: Add pdata to set mc13783-ts conversion delay

MC13783 can be programmed to wait some clock cycles between the
touchscreen polarization and the resistance conversion. This is
needed to adjust for touchscreens with high capacitance between
plates.

Signed-off-by: Michael Thalmeier <michael.thalmeier@hale.at>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>