cdc_ether: Hardwire CDC descriptors when missing

Just as ActiveSync devices, some regular RNDIS devices also lack
the CDC descriptors (e.g. devices based on BCM4320 WLAN chip).
This patch hardwires the CDC descriptors for all RNDIS style devices
when they are missing.

Signed-off-by: Bjorge Dijkstra <bjd@jooz.net>
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>