gpio: tc3589x: fix up .get_direction()

The bit in the TC3589x direction register is 0 for input
and 1 for output, but the gpiolib expects the reverse.
Fix up the logic.

Cc: stable@vger.kernel.org
Fixes: 14063d71 ("gpio: tc3589x: add .get_direction() and small cleanup")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>