diag: Update Slave processor with mask info

From 8960 onwards, application processor handles master diag. Other
slave processors can come up on different time. This change will
update each slave processor with latest mask info when it comes up.

Change-Id: Icc5f607043c8dc00dbfd504952beccaff5641f41
Signed-off-by: Shalabh Jain <shalabhj@codeaurora.org>