gpio: pl061: delete platform data handling

Platform data is a remnant of board files and all boards using
the PL061 have been migrated to use device tree or ACPI instead.
The custom mechanism to set line by default as inputs/outputs has
been superceded by the GPIO-internal hogging mechanism.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>