ARM: dts: qcom-apq8064: Fix opp table child name

The opp-320000000 name is rather misleading with the opp-hz value
of 450 MHz. Fix it!

Fixes: 8db0b6c7 ("ARM: dts: qcom: apq8064: Convert adreno from legacy gpu-pwrlevels to opp-v2")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230220120831.1591820-1-konrad.dybcio@linaro.org