util: set minimum value of nodesuspend duration to 60 seconds

Change the permissible minimum value of nodesuspend duration time
to 60 seconds. If option is less than the value, reports error.
Update virsh help and manpage the infomation.

src/util/virnodesuspend.c

@@ -90,7 +90,7 @@ static int virNodeSuspendSetNodeWakeup(unsigned long long alarmTime)
     virCommandPtr setAlarmCmd;
     int ret = -1;
 
-    if (alarmTime <= MIN_TIME_REQ_FOR_SUSPEND) {
+    if (alarmTime < MIN_TIME_REQ_FOR_SUSPEND) {
         virReportError(VIR_ERR_INVALID_ARG, "%s", _("Suspend duration is too short"));
         return -1;
     }

tools/virsh-host.c

@@ -465,7 +465,7 @@ static const vshCmdInfo info_nodesuspend[] = {
 static const vshCmdOptDef opts_node_suspend[] = {
     {"target", VSH_OT_DATA, VSH_OFLAG_REQ, N_("mem(Suspend-to-RAM), "
                                                "disk(Suspend-to-Disk), hybrid(Hybrid-Suspend)")},
-    {"duration", VSH_OT_INT, VSH_OFLAG_REQ, N_("Suspend duration in seconds")},
+    {"duration", VSH_OT_INT, VSH_OFLAG_REQ, N_("Suspend duration in seconds, at least 60")},
     {"flags", VSH_OT_INT, VSH_OFLAG_NONE, N_("Suspend flags, 0 for default")},
     {NULL, 0, 0, NULL}
 };

tools/virsh.pod

@@ -289,7 +289,8 @@ If I<cell> is specified, this will prints specified cell statistics only.
 Puts the node (host machine) into a system-wide sleep state such as
 Suspend-to-RAM, Suspend-to-Disk or Hybrid-Suspend and sets up a
 Real-Time-Clock interrupt to fire (to wake up the node) after a time delay
-specified by the 'duration' parameter.
+specified by the 'duration' parameter. The duration time should be
+at least 60 seconds.
 
 =item B<capabilities>