dt-bindings: firmware: scm: Add SM8450 compatible

Add compatible for SM8450 SoCs.

Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211201072745.3969077-3-vkoul@kernel.org