arm64: dts: qcom: sm8450: Add reserved memory nodes

Add the reserved memory nodes for SM8450. This is based on the downstream
documentation.

Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211215043440.605624-4-vkoul@kernel.org