usb: common: usb-conn-gpio: Print error on failure to get VBUS

The exact error that happened trying to get the VBUS supply can be
useful to troubleshoot what's going on.

Signed-off-by: Thierry Reding <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/common/usb-conn-gpio.c

···
 
 	if (IS_ERR(info->vbus)) {
 		if (PTR_ERR(info->vbus) != -EPROBE_DEFER)
-			dev_err(dev, "failed to get vbus\n");
+			dev_err(dev, "failed to get vbus: %ld\n", PTR_ERR(info->vbus));
 		return PTR_ERR(info->vbus);
 	}