arm64: dts: qcom: msm8916: don't use empty memory node

We expect bootloader to full memory details but passing empty values
gives warning, so add a default value

arch/arm64/boot/dts/qcom/apq8016-sbc.dt.yaml: /: memory:
	False schema does not allow {'device_type': ['memory'], 'reg': [[0, 0, 0, 0]]}

Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20210308060826.3074234-3-vkoul@kernel.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>