gpio: amdpt: Drop unneeded deref of &pdev->dev

We already have the struct device* pointer in a local variable,
so we can write this a bit shorter.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>