net: cdc_ncm: big endian fix

Probably doesn't matter much since the value is used as a
boolean anyway, but it removes the sparse warning:

 drivers/net/usb/cdc_ncm.c:1090:32: warning: incorrect type in assignment (different base types)
 drivers/net/usb/cdc_ncm.c:1090:32:    expected unsigned short [unsigned] [usertype] connected
 drivers/net/usb/cdc_ncm.c:1090:32:    got restricted __le16 [usertype] wValue

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>