arm64: dts: qcom: sdm845: rename memory@ nodes to more descriptive names

Pure effort to avoid `make dtbs_check` warnings about memory@ nodes, which
should have property device_type set to memory.

Fixes warnings as:
arch/arm64/boot/dts/qcom/sdm845-oneplus-fajita.dt.yaml: memory@f5b00000: 'device_type' is a required property
        From schema: dtschema/schemas/memory.yaml

Signed-off-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211214234648.23369-1-david@ixit.cz