Map: Display mandatory fields in msg listing with 0 parmeter mask

When message listing is done with parameter mask as 0, we should be
listing all the required fields as per map spec. Add change to set
parameter mask accordingly in Bluetooth Map code to be able fetch the
required fields.

Change-Id: I85b71ffd370518ca432907680b4f1933cf398c35
CRs-fixed: 600691