pwm: meson: Add missing spin_lock_init()

The driver uses the spin_lock but does not initialize it. Fix it.
Signed-off-by: NAxel Lin <axel.lin@ingics.com>
Acked-by: NNeil Armstrong <narmstrong@baylibre.com>
Signed-off-by: NThierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-meson.c

@@ -474,6 +474,7 @@ static int meson_pwm_probe(struct platform_device *pdev)
 	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;