soc: qcom: Introduce QMI helpers

Drivers that needs to communicate with a remote QMI service all has to
perform the operations of discovering the service, encoding and decoding
the messages and operate the socket. This introduces an abstraction for
these common operations, reducing most of the duplication in such cases.

Change-Id: I48dc7c6e0b6c83a925a8ffcf273c90ef2044a7ee
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>