ARM: dts: qcom: sdx55/sdx65: Fix CPU power-domain-names

"rpmhpd" is not documented nor used anywhere. The power-domain is used
for performance scaling (cpufreq), so "perf" is the correct name to use.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250410-dt-cpu-schema-v2-7-63d7dc9ddd0a@kernel.org


Signed-off-by: Bjorn Andersson <andersson@kernel.org>