sched/topology: Add callback to read per CPU thermal pressure

Introduce the arch_scale_thermal_pressure() callback to retrieve per CPU thermal
pressure.

Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200222005213.3873-3-thara.gopinath@linaro.org

include/linux/sched/topology.h

@@ -225,6 +225,14 @@ unsigned long arch_scale_cpu_capacity(int cpu)
 }
 #endif
 
+#ifndef arch_scale_thermal_pressure
+static __always_inline
+unsigned long arch_scale_thermal_pressure(int cpu)
+{
+	return 0;
+}
+#endif
+
 static inline int task_node(const struct task_struct *p)
 {
 	return cpu_to_node(task_cpu(p));