cpufreq: Extract cpufreq_policy_init_qos() function

cpufreq: Extract cpufreq_policy_init_qos() function

Extract the QoS-related logic from cpufreq_policy_online()
to make that function shorter/simpler.

The logic is placed in cpufreq_policy_init_qos() and is
now executed right after the following calls:

 - cpufreq_driver->init()
 - cpufreq_table_validate_and_sort()

This facilitats subsequent changes that will, in
cpufreq_policy_init_qos():

 - Set a default policy->min/max value for all policies.
 - Use the policy->min/max values set by drivers as initial request
   values for policy frequency QoS requests.

No functional change.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Reviewed-by: Jie Zhan <zhanjie9@hisilicon.com>
[ rjw: Changelog edits ]
Link: https://patch.msgid.link/20260528090913.2759118-2-pierre.gondois@arm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>