gpio: pxa: Make two symbols static

Fix sparse warnings:

drivers/gpio/gpio-pxa.c:580:29: warning:
 symbol 'pxa_irq_domain_ops' was not declared. Should it be static?
drivers/gpio/gpio-pxa.c:819:20: warning:
 symbol 'pxa_gpio_syscore_ops' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>