cpuidle: Rename X86 specific idle poll state[0] from C0 to POLL

C0 means and is well know as "not idle".
All documentation out there uses this term as "running"/"not idle"
state. Also Linux userspace tools (e.g. cpufreq-aperf and turbostat)
show C0 residency which there is correct, but means something totally
else than cpuidle "POLL" state.
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/cpuidle/cpuidle.c

@@ -181,7 +181,7 @@ static void poll_idle_init(struct cpuidle_device *dev)
 
 	cpuidle_set_statedata(state, NULL);
 
-	snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
+	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
 	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
 	state->exit_latency = 0;
 	state->target_residency = 0;