diag: Add fixes for DCI

1) Fix an issue where after running a DCI app and exiting it,
 second app does not receive any DCI data. Issue was due to
 incorrect state of a flag used by SMD channel.

2) Add a mutex around shared data structures like cumulative masks.
Multiple clients may want to change DCI mask at the same time, so
mutex will prevent any corruption

3) Add support for health commands. The client request how many logs
were dropped and received.

Change-Id: Ica12b3c93aa4dda9b04aa13cd5a9f8dbc412148c
Signed-off-by: Shalabh Jain <shalabhj@codeaurora.org>