samples: Introduce Qualcomm QRTR sample client

Introduce a sample driver that register for server notifications and
spawn clients for each available test service (service 15). The spawned
clients implements the interface for encoding "ping" and "data" requests
and decode the responses from the remote.

Change-Id: I9a04571f780813cb377f37f5e02b0a0056038793
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Patch-mainline: linux-arm-msm @ 04/08/17, 7:59
Signed-off-by: Chris Lew <clew@codeaurora.org>