gpio: Add missing spin_lock_init in gpio-pch driver

This bug was introduced by commit d568a681
"gpio-pch: add spinlock in suspend/resume processing"
which adds a spinlock to struct pch_gpio but never init the spinlock.
Reported-by: Tomoya MORINAGA <tomoya.rohm@gmail.com>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/gpio/gpio-pch.c

@@ -392,6 +392,7 @@ static int __devinit pch_gpio_probe(struct pci_dev *pdev,
 	chip->reg = chip->base;
 	pci_set_drvdata(pdev, chip);
 	mutex_init(&chip->lock);
+	spin_lock_init(&chip->spinlock);
 	pch_gpio_setup(chip);
 	ret = gpiochip_add(&chip->gpio);
 	if (ret) {