mfd: ti_am335x_tscadc: Don't mark TSCADC MFD as wakeup capable

Currently tscadc MFD is marked as wakeup capable which incorrect
because, its actually touch event by child TSC device that wakes up the
system. Therefore, remove device_init_wakeup() call that marks TSCADC
device as wakeup capable in favor of moving to mark TSC input device as
wakeup capable later.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>