trace: rtb: add msm_rtb register tracing feature snapshot

This is a snapshot of the msm_rtb driver from kernel/trace taken as of
msm-4.14 commit <55e5efd553c10ef>.(Merge "nl80211: Fix external_auth
check for offloaded authentication")

Change-Id: Ib6a141a81ba42ed895880cb2a3c4b4a2c3efe541
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>