yosemite4: virtual-sensor: adjust formula of airflow sensor

Different airbaffle design in DVT stage cause higher impedance and lower
airflow curve in DVT chassis.
Therefore, need to adjust the formula of airflow sensor.

Tested:
Checked the sensor value is correct by thermal team.

Change-Id: Ia83cb267a6351f3f197bb86451b6c029ab4597a0
Signed-off-by: Ricky CX Wu <ricky.cx.wu.wiwynn@gmail.com>
diff --git a/meta-facebook/meta-yosemite4/recipes-phosphor/sensors/phosphor-virtual-sensor/virtual_sensor_config.json b/meta-facebook/meta-yosemite4/recipes-phosphor/sensors/phosphor-virtual-sensor/virtual_sensor_config.json
index 751184d..1fb3b32 100644
--- a/meta-facebook/meta-yosemite4/recipes-phosphor/sensors/phosphor-virtual-sensor/virtual_sensor_config.json
+++ b/meta-facebook/meta-yosemite4/recipes-phosphor/sensors/phosphor-virtual-sensor/virtual_sensor_config.json
@@ -476,7 +476,7 @@
                 }
             ]
         },
-        "Expression": "(((P1 + P2 + P3 + P4 + P5 + P6 + P7 + P8 + P9 + P10 + P11 + P12 + P13 + P14 + P15 + P16 + P17 + P18 + P19 + P20 + P21 + P22 + P23 + P24) / 24) * 0.0725) - 14.5"
+        "Expression": "(((P1 + P2 + P3 + P4 + P5 + P6 + P7 + P8 + P9 + P10 + P11 + P12 + P13 + P14 + P15 + P16 + P17 + P18 + P19 + P20 + P21 + P22 + P23 + P24) / 24) * 0.0702) - 16.9"
     },
     {
         "Desc": {