usb: dwc3: meson-g12a: fix suspend resume regulator unbalanced disables

When going in suspend, in Device mode, then resuming back leads
to the following:

unbalanced disables for USB_PWR_EN
WARNING: CPU: 0 PID: 163 at ../drivers/regulator/core.c:2590 _regulator_disable+0x104/0x180
Hardware name: Amlogic Meson G12A U200 Development Board (DT)
[...]
pc : _regulator_disable+0x104/0x180
lr : _regulator_disable+0x104/0x180
[...]
Call trace:
 _regulator_disable+0x104/0x180
 regulator_disable+0x40/0x78
 dwc3_meson_g12a_otg_mode_set+0x84/0xb0
 dwc3_meson_g12a_irq_thread+0x58/0xb8
 irq_thread_fn+0x28/0x80
 irq_thread+0x118/0x1b8
 kthread+0xf4/0x120
 ret_from_fork+0x10/0x18

This disables the regulator if enabled on suspend, and the reverse on
resume.

Fixes: c9999337 ("usb: dwc3: Add Amlogic G12A DWC3 glue")
Tested-by: Kevin Hilman <khilman@baylibre.com>
Reported-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/dwc3-meson-g12a.c

@@ -562,7 +562,13 @@ static int __maybe_unused dwc3_meson_g12a_runtime_resume(struct device *dev)
 static int __maybe_unused dwc3_meson_g12a_suspend(struct device *dev)
 {
 	struct dwc3_meson_g12a *priv = dev_get_drvdata(dev);
-	int i;
+	int i, ret;
+
+	if (priv->vbus && priv->otg_phy_mode == PHY_MODE_USB_HOST) {
+		ret = regulator_disable(priv->vbus);
+		if (ret)
+			return ret;
+	}
 
 	for (i = 0 ; i < PHY_COUNT ; ++i) {
 		phy_power_off(priv->phys[i]);
@@ -597,6 +603,12 @@ static int __maybe_unused dwc3_meson_g12a_resume(struct device *dev)
 			return ret;
 	}
 
+       if (priv->vbus && priv->otg_phy_mode == PHY_MODE_USB_HOST) {
+               ret = regulator_enable(priv->vbus);
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }