net: Add snapshot of sockev module

This is a snapshot of the sockev module taken as of msm-4.4
commit 33193859886dd87 ("net: core: Send only BIND and LISTEN events.").

Added module which subscribes to socket notifier events. Notifier events
are then converted to a multicast netlink message for user space
applications to consume.

CRs-Fixed: 1078373
Change-Id: If72b7c9a127d3861d276b681b052be3619bc6562
Acked-by: Manoj Basapathi <manojbm@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: Tejaswi Tanikella <tejaswit@codeaurora.org>