Removed unused variable from sds.c
Removed unused variable from sds.c

Related to coverity report:
/root/openscap/src/DS/sds.c:780: returned_pointer: Pointer
"component_ref" returned by "ds_sds_find_component_ref(datastream,
cref_id)" is never used.

redhatrises/openscap,openprivacy/openscap,isimluk/openscap,jan-cerny/openscap,postfix/openscap,OpenSCAP/openscap,OpenSCAP/openscap,openprivacy/openscap,ybznek/openscap,mpreisler/openscap,isimluk/openscap,postfix/openscap,ybznek/openscap,jan-cerny/openscap,jan-cerny/openscap,mpreisler/openscap,mpreisler/openscap,redhatrises/openscap,jan-cerny/openscap,Hexadorsimal/openscap,ybznek/openscap,Hexadorsimal/openscap,ybznek/openscap,ybznek/openscap,jan-cerny/openscap,ybznek/openscap,Hexadorsimal/openscap,mpreisler/openscap,openprivacy/openscap,OpenSCAP/openscap,Hexadorsimal/openscap,Hexadorsimal/openscap,mpreisler/openscap,jan-cerny/openscap,Hexadorsimal/openscap,isimluk/openscap,postfix/openscap,OpenSCAP/openscap,openprivacy/openscap,postfix/openscap,postfix/openscap,redhatrises/openscap,openprivacy/openscap,isimluk/openscap,redhatrises/openscap,postfix/openscap,OpenSCAP/openscap,OpenSCAP/openscap,isimluk/openscap,openprivacy/openscap,redhatrises/openscap,isimluk/openscap,redhatrises/openscap,mpreisler/openscap