Add an implementation of the SCM interface that works on ARM64 SoCs.  This
is used by things like determine if we have HDCP support or not on the
system.
Signed-off-by: NKumar Gala <galak@codeaurora.org>
Signed-off-by: NAndy Gross <andy.gross@linaro.org>
Reviewed-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: NStephen Boyd <sboyd@codeaurora.org>