rndis_host: Add RNDIS physical medium checking into generic_rndis_bind()

Add RNDIS physical medium checking into generic_rndis_bind() and also make
rndis_host to be only bind on every medium except wireless.

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>