CHROMIUM: ath10k: Relayfs implementation for RTT capture

RTT meta data will be built from HTT event and followed by that RTT
capture will carried to relayfs.

/sys/kernel/debug/ieee80211/phyX/ath10k/rtt_dump0

Below is the RTT dump format for relayfs,

<Magic Number><RTT Meta data><RTT capture><Magic Number>

BUG=b:132147953
TEST=None

Change-Id: I72033690daf2c02b0ccba2f6771442ee8318ad12
Signed-off-by: Yi Chen <yichen@codeaurora.org>
Signed-off-by: Vamsi Singamsetty <vamssi@codeaurora.org>