msm: adsprpc: Driver capability

Allows the client to query the driver for driver capabilities.
Helpful for maintaining backwards compatibility in future.

Acked-by: Deepika Singh <dsi@qti.qualcomm.com>
Change-Id: I82b2e05eae0241dd8cef22f07845998cae739395
Signed-off-by: Mohammed Nayeem Ur Rahman <mohara@codeaurora.org>