pwm: meson: Add missing spin_lock_init()

The driver uses the spin_lock but does not initialize it. Fix it.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
index 381871b..9d5bd7d 100644
--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -474,6 +474,7 @@
 	if (IS_ERR(meson->base))
 		return PTR_ERR(meson->base);
 
+	spin_lock_init(&meson->lock);
 	meson->chip.dev = &pdev->dev;
 	meson->chip.ops = &meson_pwm_ops;
 	meson->chip.base = -1;