UPSTREAM: usb: gadget: move gadget API functions to udc-core

instead of defining all functions as static inlines,
let's move them to udc-core and export them with
EXPORT_SYMBOL_GPL, that way we can make sure that
only GPL drivers will use them.

As a side effect, it'll be nicer to add tracepoints
to the gadget API.

While at that, also fix Kconfig dependencies to
avoid randconfig build failures.

Change-Id: I3fcc99c0730608076cfa8624908e58b7ee6f1bef
Acked-By: Sebastian Reichel <sre@kernel.org>
Acked-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: William Wu <william.wu@rock-chips.com>
(cherry-picked from commit 5a8d651a2bde01e00caf78496390d6ae46df80af)

Author: Felipe Balbi

drivers/phy/Kconfig

@@ -159,6 +159,7 @@ config TWL4030_USB
 	tristate "TWL4030 USB Transceiver Driver"
 	depends on TWL4030_CORE && REGULATOR_TWL4030 && USB_MUSB_OMAP2PLUS
 	depends on USB_SUPPORT
+	depends on USB_GADGET || !USB_GADGET # if USB_GADGET=m, this can't 'y'
 	select GENERIC_PHY
 	select USB_PHY
 	help

drivers/power/Kconfig

@@ -309,6 +309,7 @@ config BATTERY_RX51
 config CHARGER_ISP1704
 	tristate "ISP1704 USB Charger Detection"
 	depends on USB_PHY
+	depends on USB_GADGET || !USB_GADGET # if USB_GADGET=m, this can't be 'y'
 	help
 	  Say Y to enable support for USB Charger Detection with
 	  ISP1707/ISP1704 USB transceivers.