dt-bindings: firmware: scm: Add MSM8998 and SDM845

Now that the compatible/clock handling is reworked add compatibles for
MSM8998 and SDM845 to the SCM binding.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>