Add device binding documentation for Qualcomm Technology Inc's RPMH RSC
driver. The driver is used for communicating resource state requests for
shared resources.

Cc: devicetree@vger.kernel.org
Signed-off-by: Lina Iyer <ilina@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
[rplsssn@codeaurora.org: minor order correction for TCS type]
Signed-off-by: Raju P.L.S.S.S.N <rplsssn@codeaurora.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>