USB: usb gadget stack can now -DDEBUG with Kconfig

Although the other USB driver directories got taught how use Kconfig
and the Makefile to enable the debugging messages enabled by -DDEBUG,
the gadget stack was overlooked.

This patch remedies that omission, but doesn't update any drivers to
remove previous idiosyncracies in this area ... other than the RNDIS
code, which defined its own DEBUG() macro in a broken way.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Kconfig

@@ -42,6 +42,20 @@ config USB_GADGET
 	   For more information, see <http://www.linux-usb.org/gadget> and
 	   the kernel DocBook documentation for this API.
 
+config USB_GADGET_DEBUG
+	boolean "Debugging messages"
+	depends on USB_GADGET && DEBUG_KERNEL && EXPERIMENTAL
+	help
+	   Many controller and gadget drivers will print some debugging
+	   messages if you use this option to ask for those messages.
+
+	   Avoid enabling these messages, even if you're actively
+	   debugging such a driver.  Many drivers will emit so many
+	   messages that the driver timings are affected, which will
+	   either create new failure modes or remove the one you're
+	   trying to track down.  Never enable these messages for a
+	   production build.
+
 config USB_GADGET_DEBUG_FILES
 	boolean "Debugging information files"
 	depends on USB_GADGET && PROC_FS

drivers/usb/gadget/Makefile

 #
 # USB peripheral controller drivers
 #
+ifeq ($(CONFIG_USB_GADGET_DEBUG),y)
+	EXTRA_CFLAGS		+= -DDEBUG
+endif
+
 obj-$(CONFIG_USB_DUMMY_HCD)	+= dummy_hcd.o
 obj-$(CONFIG_USB_NET2280)	+= net2280.o
 obj-$(CONFIG_USB_PXA2XX)	+= pxa2xx_udc.o