msm: qdss: add STM driver

System Trace Macrocell (STM) driver provides apis and user interfaces
that can be used for software instrumentation based tracing that takes
advantage of the STM hardware.

Change-Id: I63c56bf8c6a86ec0ad49950d631be8db6074d7a8
Signed-off-by: Pratik Patel <pratikp@codeaurora.org>