Gpio/trivial: replace numeric with standard PM state macros

Use standard PM state macros PCI_Dx instead of numeric 0/1/2..

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Cc: Michael Buesch <m@bues.ch>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Jiri Kosina <trivial@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>