arm64: dts: qcom: msm8998: Use rpmpd definitions for opp table levels

arm64: dts: qcom: msm8998: Use rpmpd definitions for opp table levels

The dt-bindings/power/qcom-rpmpd.h header is being included in this
DT but the RPMPD OPP table declarations were using open-coded values:
use the definitions found in the aforementioned header.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Link: https://lore.kernel.org/r/20210109160759.186990-1-angelogioacchino.delregno@somainline.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>