ANDROID: netfilter: xt_qtaguid: Use sk_callback_lock read locks before reading sk->sk_socket

It prevents a kernel panic when accessing sk->sk_socket fields due to NULLing sk->sk_socket when sock_orphan is called through
sk_common_release.

Change-Id: I4aa46b4e2d8600e4d4ef8dcdd363aa4e6e5f8433
Signed-off-by: Mohamad Ayyash <mkayyash@google.com>
(cherry picked from commit cdea0ebcb8bcfe57688f6cb692b49e550ebd9796)
Signed-off-by: John Stultz <john.stultz@linaro.org>