Fixed erroneous use of HOST_SETTINGS in utils.robot.
Fixed erroneous use of HOST_SETTINGS in utils.robot.

The correct variable name is HOST_SETTING (singular).
Resolves openbmc/openbmc-test-automation#492

Change-Id: I2b659a56989034c580c8e44d0e539d2919a6ee84
Signed-off-by: Sridevi Ramesh <cb5e1f81dd390dfc3a9afc08ab7298b7ab4296f5@in.ibm.com>

openbmc/openbmc-test-automation,openbmc/openbmc-test-automation