Revert "drivers/misc/ti-st: remove gpio handling"

Revert "drivers/misc/ti-st: remove gpio handling"

This reverts commit eccf2979b2c034b516e01b8a104c3739f7ef07d1.

The reason is that it broke TI WiLink shared transport on Panda.
Also, callback functions should not be added to board files anymore,
so revert to implementing the power functions in the driver itself.

Additionally, changed a variable name ('status' to 'err') so that this
revert compiles properly.

Cc: stable <stable@vger.kernel.org> [3.7]
Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>