net: qrtr: Move constants to header file

The constants are used by both the name server and clients, so clarify
their value and move them to the uapi header.

Change-Id: I670694bb1ab71eace1efa186bcdf097b7a920653
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Patch-mainline: netdev @ 06/09/17, 23:03
Signed-off-by: Chris Lew <clew@codeaurora.org>