gpio: amd-fch: correct logic of GPIO_LINE_DIRECTION

The original commit appears to have the logic reversed in
amd_fch_gpio_get_direction. Also confirmed by observing the value of
"direction" in the sys tree.

Signed-off-by: Ed Wildgoose <lists@wildgooses.com>
Fixes: e09d168f ("gpio: AMD G-Series PCH gpio driver")
Cc: stable@vger.kernel.org
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>