Input: ti_am335x_tsc: Mark TSC device as wakeup source

Instead of TSCADC MFD device, mark TSC as wakeup source and change all
wakeup related PM calls to operate on TSC device.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>