intel_pstate: Declare pid_params/pstate_funcs/hwp_active __read_mostly

pid_params is written once by copy_pid_params() during initialization,
and thereafter is mostly read by hot path intel_pstate_update_util().
The read of pid_params gets more after commit a4675fbc4a7a ("cpufreq:
intel_pstate: Replace timers with utilization update callbacks")

pstate_funcs is written once by copy_cpu_funcs() during initialization,
and thereafter is mostly read by hot path intel_pstate_update_util()

hwp_active is written to once during initialization and thereafter is
mostly read by hot path intel_pstate_update_util().

The fact that they are mostly read and not written to makes them
candidates for __read_mostly declarations.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -282,9 +282,9 @@ struct cpu_defaults {
 static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu);
 static inline int32_t get_target_pstate_use_cpu_load(struct cpudata *cpu);
 
-static struct pstate_adjust_policy pid_params;
-static struct pstate_funcs pstate_funcs;
-static int hwp_active;
+static struct pstate_adjust_policy pid_params __read_mostly;
+static struct pstate_funcs pstate_funcs __read_mostly;
+static int hwp_active __read_mostly;
 
 #ifdef CONFIG_ACPI
 static bool acpi_ppc;