mfd: Put WM8994 into reset when suspending

Ensure that the chip is in the lowest power mode possible when suspended
by performing a soft reset on it. On early silicon revisions the lowest
power modes can't be entered without using reset so we can't achieve
equivalent results within the individual drivers.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

drivers/mfd/wm8994-core.c

@@ -271,6 +271,11 @@ static int wm8994_suspend(struct device *dev)
 	if (ret < 0)
 		dev_err(dev, "Failed to save LDO registers: %d\n", ret);
 
+	/* Explicitly put the device into reset in case regulators
+	 * don't get disabled in order to ensure consistent restart.
+	 */
+	wm8994_reg_write(wm8994, WM8994_SOFTWARE_RESET, 0x8994);
+
 	wm8994->suspended = true;
 
 	ret = regulator_bulk_disable(wm8994->num_supplies,