usb: gadget: Kconfig: use bool instead of boolean

Keyword 'boolean' for type definition attributes is considered
deprecated and, therefore, should not be used anymore.

See http://lkml.kernel.org/r/cover.1418003065.git.cj@linux.com
See http://lkml.kernel.org/r/1419108071-11607-1-git-send-email-cj@linux.comSigned-off-by: Christoph Jaeger <cj@linux.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/Kconfig

@@ -424,7 +424,7 @@ config USB_CONFIGFS_F_HID
 	  For more information, see Documentation/usb/gadget_hid.txt.
 
 config USB_CONFIGFS_F_UVC
-	boolean "USB Webcam function"
+	bool "USB Webcam function"
 	depends on USB_CONFIGFS
 	depends on VIDEO_DEV
 	select VIDEOBUF2_VMALLOC