net: fill in MODULE_DESCRIPTION()s under net/802*

W=1 builds now warn if module is built without a MODULE_DESCRIPTION().

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>