phy: sun4i-usb: Support set_mode to USB_HOST for non-OTG PHYs

commit 1396929e upstream.

While only the first PHY supports mode switching, the remaining PHYs
work in USB host mode. They should support set_mode with mode=USB_HOST
instead of failing. This is especially needed now that the USB core does
set_mode for all USB ports, which was added in commit b97a3134 ("usb:
core: comply to PHY framework").

Make set_mode with mode=USB_HOST a no-op instead of failing for the
non-OTG USB PHYs.

Fixes: 6ba43c29 ("phy-sun4i-usb: Add support for phy_set_mode")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/phy/allwinner/phy-sun4i-usb.c

@@ -480,8 +480,11 @@ static int sun4i_usb_phy_set_mode(struct phy *_phy, enum phy_mode mode)
 	struct sun4i_usb_phy_data *data = to_sun4i_usb_phy_data(phy);
 	int new_mode;
 
-	if (phy->index != 0)
+	if (phy->index != 0) {
+		if (mode == PHY_MODE_USB_HOST)
+			return 0;
 		return -EINVAL;
+	}
 
 	switch (mode) {
 	case PHY_MODE_USB_HOST: