gpio: xgene: Fix missing spin_lock_init()

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpio-xgene.c b/drivers/gpio/gpio-xgene.c
index 150e7f1..35104fd 100644
--- a/drivers/gpio/gpio-xgene.c
+++ b/drivers/gpio/gpio-xgene.c
@@ -189,6 +189,7 @@
 
 	gpio->chip.ngpio = XGENE_MAX_GPIOS;
 
+	spin_lock_init(&gpio->lock);
 	gpio->chip.dev = &pdev->dev;
 	gpio->chip.direction_input = xgene_gpio_dir_in;
 	gpio->chip.direction_output = xgene_gpio_dir_out;