kselftests: add cpupower to RDEPENDS
kselftests: add cpupower to RDEPENDS

Kselftests intel_pstate uses cpupower.

test intel_pstate uses cpupower, add that to RDEPEND
cd /opt/kselftests/default-in-kernel/intel_pstate
./run.sh
./run.sh: line 79: cpupower: command not found

Looked at commit below from meta-rpb
79beb20ef4a9 ("kselftests-common: fix RDEPENDS on cpupower")
URL:
https://github.com/96boards/meta-rpb/commit/79beb20ef4a94b7f3b1c07aa89a2db67ff178673

Signed-off-by: Anders Roxell <b4e8e89057bc64bc4f9625a4a821c9ac177a7ed2@linaro.org>

96boards/meta-96boards,kraj/meta-96boards,mrchapp/meta-96boards,kraj/meta-96boards