[ Upstream commit e1558a93 ]

Add missing .owner of struct pppox_proto. This prevents the
module from being removed from underneath its users.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>