cpufreq: Introduce policy_set_boost()

Introduce policy_set_boost() to update boost state of a cpufreq policy.

No intentional function change.

Reviewed-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://patch.msgid.link/1863178ac17340c810519c8593014b8e561797ea.1745511526.git.viresh.kumar@linaro.org


Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>