get selinux context on add call arrival.

interfaceChain may take too long and allow for the PID
to become invalidated.

Bug: 68217907
Test: hidl's run_all_device_tests, boot + camera/YT sanity
Merged-In: Ie69d92f9006d10e7e3e4871f5760823291ed8e1f
Change-Id: Ie69d92f9006d10e7e3e4871f5760823291ed8e1f
(cherry picked from commit 8165cd3e0044896bed17be2c580d60bc93b4ed2b)
3 files changed