hal: Fix memory leak in HAL debug logs

String returned from str_parms_to_str for set/get parameter in
debug logs is not de-allocated. Fix is to make sure the memory
allocated for set parameter key value pair is de-allocated.

CRs-Fixed: 610079
Change-Id: I5027d8f1741c9e7223e7b4721f8d5473404998d3