usb gadget: USB_GADGET_VBUS_DRAW Kconfig option

Offer a "how much VBUS power to request" configuration option
for USB gadgets that aren't using board-specific customization
of their gadget or (composite) configuration drivers.

Also remove a couple pointless "depends on USB_GADGET" bits
from the Kconfig text; booleans inside an "if USB_GADGET" will
already have that dependency.

Based on a patch from Justin Clacherty.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Justin Clacherty <justin@redfish-group.com>
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/gadget/printer.c b/drivers/usb/gadget/printer.c
index 00b7ed5..5a3034f 100644
--- a/drivers/usb/gadget/printer.c
+++ b/drivers/usb/gadget/printer.c
@@ -252,7 +252,7 @@
 	.bConfigurationValue =	DEV_CONFIG_VALUE,
 	.iConfiguration =	0,
 	.bmAttributes =		USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER,
-	.bMaxPower =		1	/* Self-Powered */
+	.bMaxPower =		CONFIG_USB_GADGET_VBUS_DRAW / 2,
 };
 
 static struct usb_interface_descriptor intf_desc = {
@@ -1476,7 +1476,6 @@
 	if (gadget->is_otg) {
 		otg_desc.bmAttributes |= USB_OTG_HNP,
 		config_desc.bmAttributes |= USB_CONFIG_ATT_WAKEUP;
-		config_desc.bMaxPower = 4;
 	}
 
 	spin_lock_init(&dev->lock);