Support derivative term in PID algorithm and support to set cycle interval time from fan table

1. Support to calculate derivative term in PID algorithm.
2. Add two properties: cycleIntervalTimeMS and updateThermalsTimeMS
in fan table that could be used to decide "time interval of PID control loop"
and "time interval to update thermals' cached value".

Tested:

- PID algorithm:
    1. Check pid-control-service could calculate output PWM
       according to the fan table.

	[Test log]
        root@greatlakes:~# systemctl status phosphor-pid-control -l
        * phosphor-pid-control.service - Phosphor-Pid-Control Margin-based Fan Control Daemon
             Loaded: loaded (/lib/systemd/system/phosphor-pid-control.service; enabled; preset: enabled)
             Active: active (running) since Fri 2018-03-09 05:09:35 PST; 1min 47s ago
           Main PID: 3105 (swampd)
             CGroup: /system.slice/phosphor-pid-control.service
                     `-3105 /usr/bin/swampd -c /usr/share/entity-manager/configurations/fan-table.json
        ...
        Mar 09 05:10:29 greatlakes phosphor-pid-control[3105]: PID Zone 1 max SetPoint 3.75 requested by
        PID_NIC_SENSOR_TEMP BMC_SENSOR_FAN0_TACH BMC_SENSOR_FAN2_TACH BMC_SENSOR_FAN4_TACH BMC_SENSOR_FAN6_TACH

- Cycle interval time:
    1. Set cycleIntervalTimeMS and updateThermalsTimeMS
       to 1000 ms in fan table
    2. Check service would update thermal every second from debug log.

	[Test log]
        root@greatlakes:~# journalctl -u phosphor-pid-control --since "Mar 09 04:52:16"
        Mar 09 04:52:16 greatlakes systemd[1]: Started Phosphor-Pid-Control Margin-based Fan Control Daemon.
        ...
        Mar 09 04:53:28 greatlakes phosphor-pid-control[2795]: processThermals
        Mar 09 04:53:28 greatlakes phosphor-pid-control[2795]: processFans
        Mar 09 04:53:29 greatlakes phosphor-pid-control[2795]: processThermals
        Mar 09 04:53:29 greatlakes phosphor-pid-control[2795]: processFans
        Mar 09 04:53:30 greatlakes phosphor-pid-control[2795]: processThermals
        Mar 09 04:53:30 greatlakes phosphor-pid-control[2795]: processFans

Change-Id: I04e1b440603c3ad66a1e26c96451992785da6fe6
Signed-off-by: Bonnie Lo <Bonnie_Lo@wiwynn.com>
diff --git a/pid/util.cpp b/pid/util.cpp
index 646376d..ac6edb1 100644
--- a/pid/util.cpp
+++ b/pid/util.cpp
@@ -29,6 +29,7 @@
     info->ts = initial.ts;
     info->proportionalCoeff = initial.proportionalCoeff;
     info->integralCoeff = initial.integralCoeff;
+    info->derivativeCoeff = initial.derivativeCoeff;
     info->feedFwdOffset = initial.feedFwdOffset;
     info->feedFwdGain = initial.feedFwdGain;
     info->integralLimit.min = initial.integralLimit.min;
@@ -46,6 +47,7 @@
     std::cerr << " ts: " << info->ts
               << " proportionalCoeff: " << info->proportionalCoeff
               << " integralCoeff: " << info->integralCoeff
+              << " derivativeCoeff: " << info->derivativeCoeff
               << " feedFwdOffset: " << info->feedFwdOffset
               << " feedFwdGain: " << info->feedFwdGain
               << " integralLimit.min: " << info->integralLimit.min
@@ -54,6 +56,7 @@
               << " outLim.max: " << info->outLim.max
               << " slewNeg: " << info->slewNeg << " slewPos: " << info->slewPos
               << " last_output: " << info->lastOutput
+              << " last_error: " << info->lastError
               << " integral: " << info->integral << std::endl;
 
     return;