soc: qcom: smd-rpm: Add msm8996 compatibility

With the RPM driver transitioned to RPMSG we can reuse the SMD-RPM
driver ontop of GLINK for 8996, without any modifications.

Acked-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>