pinctrl: sirf: drop pointless static qualifier in sirfsoc_gpio_probe

There is no need to have the 'sgpio' variable static since new
value always be assigned before use it.

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