Fix Segv on unknown address error flagged by fuzzer test.

The error is thrown when the destructor tries to free pointer memory.
This is happening for cases where the pointer was not initialized. Initializing it to a default value fixes the error.

Bug: 245135112
Test: Build mtp_host_property_fuzzer and run on the target device
Change-Id: I255cd68b7641e96ac47ab81479b9b46b78c15580