Change detected class instance validation check

Change detected class instance validation check

changed from target name to malware name.
In case of scan data, target name can be empty by default so
we cannot validate with target name's emptiness.
Malware name field is mandatory so always filled if detected
item is valid.

Change-Id: I7e2444019fa773e763910a1e83090bf9a705dc4e
Signed-off-by: Kyungwook Tak <k.tak@samsung.com>