drivers/misc/ti-st: remove gpio handling

A platform hook to enable/disable the chip was introduced to perform specific
activities to power-up and power-down the WL chip.
Moving the power-up/down sequence also there makes more sense, since different
platforms have begun to have their own ways to power-up/down the chip.
This patch removes all of the gpio handling done by the driver in
st_kim_start/st_kim_stop & any of the gpio request done in the probe function.

Signed-off-by: Pavan Savoy <pavan_savoy@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>