netfilter: xt_TEE: add missing code to get interface index in checkentry.

checkentry(tee_tg_check) should initialize priv->oif from dev if possible.
But only netdevice notifier handler can set that.
Hence priv->oif is always -1 until notifier handler is called.

CRs-fixed: 2411945
Change-Id: I5bba551e0e892dc633ac07056000310b362a41ad
Fixes: 9e2f6c5d ("netfilter: Rework xt_TEE netdevice notifier")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Git-commit: 18c0ab87364ac5128a152055fdcb1d27e01caf01
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>