net: cdc_ncm: Fix build error

If USB_NET_CDC_NCM is y and USB_NET_CDCETHER is m, build fails:

drivers/net/usb/cdc_ncm.o:(.rodata+0x1d8): undefined reference to `usbnet_cdc_update_filter'

Select USB_NET_CDCETHER for USB_NET_CDC_NCM to fix this.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: e10dcb1b ("net: cdc_ncm: hook into set_rx_mode to admit multicast traffic")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>