diag: Add mdlog session to apps pkt response path

Apps pkt cmd response defaults to APPS_DATA peripheral.
Error response for mdlogging does not go to the right md
session. Pass md session along response path to ensure
correct destination.

Change-Id: Iece75fdb580a68350085bf48df374e60c2b4adb6
Signed-off-by: Chris Lew <clew@codeaurora.org>