diag: dci: Extend DCI support to remote processors

DCI is now supported on the remote processors. Make changes to
the DCI logic in diag driver to allow clients to register with
remote processors for diag data.

Change-Id: I15dc4b63f2d8fa4e7a1f4f2307b25a5dcddfaa1a
Signed-off-by: Ravi Aravamudhan <aravamud@codeaurora.org>