samples: Introduce Qualcomm QMI 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: I92659781b5fcfbfb51175fe742f5767459b43f9d
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Patch-mainline: linux-arm-msm @ 15/11/2017 12:10
[clew@codeaurora.org: Merge differences between v1 and v3 patchsets
 from "samples: Introduce Qualcomm QMI sample client"]
Signed-off-by: Chris Lew <clew@codeaurora.org>