RDKB-37224 : Removing null string output of AssociatedDevice parameter
RDKB-37224 : Removing null string output of AssociatedDevice parameter

Reason for change: AssociatedDevice parameter should return empty string instead of null.
Test Procedure: As mentioned in the ticket
Risks: None

Signed-off-by: c6a2df48e7e61e58f2efa28fde6cc100dbea4fb2@comcast.com
(cherry picked from commit bac6e8f2c1e8e46a6af2cd7556f72b22b6a254f8)
Change-Id: Ie57f38328639152976a3395872dedebf3a672f23

rdkcmf/rdkb-CcspLMLite,rdkcmf/rdkb-CcspLMLite,rdkcmf/rdkb-CcspLMLite