diag: Add checks before sending real time mask updates

Check peripheral buffering state before sending real time
control packet. Do not send real time update if one of the peripherals
is in buffering mode.

Change-Id: Ie8f59e8709f71a4b5c23c33a07174d2325e8fafb
Signed-off-by: Ravi Aravamudhan <aravamud@codeaurora.org>