diag: dci: DCI setting event_config variable incorrectly

Diag driver is always setting event_config variable to 1
on DCI channel due to which diag_masks_enabled API is
returning TRUE even when all the event masks are 0. This
patch sets event_config variable to 0 when all the event
masks are 0.

Change-Id: Iafe20c5b785ef6e31db531ad4fc5663f54dceb48
CRs-Fixed: 572884
Signed-off-by: Mohit Aggarwal <maggarwa@codeaurora.org>