cpufreq: intel_pstate: Change intel_pstate_get_hwp_max() argument

All of the callers of intel_pstate_get_hwp_max() access the struct
cpudata object that corresponds to the given CPU already and the
function itself needs to access that object (in order to update
hwp_cap_cached), so modify the code to pass a struct cpudata pointer
to it instead of the CPU number.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Chen Yu <yu.c.chen@intel.com>