cpupower: Enable disabled Cstates if they are below max latency

cpupower idle-set -D <latency>
currently only disables all C-states that have a higher latency than the
specified <latency>. But if deep sleep states were already disabled and
have a lower latency, they should get enabled again.

For example:
This call:
cpupower idle-set -D 30
disables all C-states with a higher or equal latency than 30.
If one then calls:
cpupower idle-set -D 100
C-states with a latency between 30-99 will get enabled again with this patch
now. It is ensured that only C-states with a latency of 100 and higher are
disabled.

Signed-off-by: Thomas Renninger <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

tools/power/cpupower/man/cpupower-idle-set.1

···
 Enable a specific processor sleep state.
 .TP
 \fB\-D\fR \fB\-\-disable-by-latency\fR <LATENCY>
-Disable all idle states with a equal or higher latency than <LATENCY>
+Disable all idle states with a equal or higher latency than <LATENCY>.
+
+Enable all idle states with a latency lower than <LATENCY>.
 .TP
 \fB\-E\fR \fB\-\-enable-all\fR
 Enable all idle states if not enabled already.

tools/power/cpupower/utils/cpuidle-set.c

···
 					(cpu, idlestate);
 				state_latency = sysfs_get_idlestate_latency
 					(cpu, idlestate);
-				if (disabled == 1 || latency > state_latency)
+				if (disabled == 1) {
+					if (latency > state_latency){
+						ret = sysfs_idlestate_disable
+							(cpu, idlestate, 0);
+						if (ret == 0)
+		printf(_("Idlestate %u enabled on CPU %u\n"),  idlestate, cpu);
+					}
 					continue;
-				ret = sysfs_idlestate_disable
-					(cpu, idlestate, 1);
-				if (ret == 0)
+				}
+				if (latency <= state_latency){
+					ret = sysfs_idlestate_disable
+						(cpu, idlestate, 1);
+					if (ret == 0)
 		printf(_("Idlestate %u disabled on CPU %u\n"), idlestate, cpu);
+				}
 			}
 			break;
 		case 'E':