staging: wusbcore: Fix build error without CONFIG_USB

USB_WUSB should depends on CONFIG_USB, otherwise building fails

drivers/staging/wusbcore/wusbhc.o: In function `wusbhc_giveback_urb':
wusbhc.c:(.text+0xa28): undefined reference to `usb_hcd_giveback_urb'

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 71ed79b ("USB: Move wusbcore and UWB to staging as it is obsolete")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20190809102150.66896-1-yuehaibing@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wusbcore/Kconfig

@@ -4,7 +4,7 @@
 #
 config USB_WUSB
 	tristate "Enable Wireless USB extensions"
-	depends on UWB
+	depends on UWB && USB
 	select CRYPTO
 	select CRYPTO_AES
 	select CRYPTO_CCM