cpufreq: arm_scmi: Constify scmi_perf_ops pointers

[ Upstream commit 69ecb323 ]

The perf_ops are not modified through this pointer. Make them const to
indicate that. This is in preparation to make the scmi-ops pointers in
scmi_handle const.

Link: https://lore.kernel.org/r/20200906230452.33410-2-rikard.falkeborn@gmail.com


Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>