sensorhandler: changed mutabiltity error code in get sensor
sensorhandler: changed mutabiltity error code in get sensor

Changed mutability handling error code in get sensor
from IPMI_CC_SENSOR_INVALID to IPMI_CC_ILLEGAL_COMMAND

Change-Id: I599de08e3d3bc6a9820ac3978f0a4d160f19f55e
Signed-off-by: Jayanth Othayoth <d8c0d7e9f313f85e22ced997a3958fcdeb1cb606@in.ibm.com>

openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid