diag: Update remote address for each CNTL packet

Possibility of stale remote address for CNTL channel is
prevented by updating address for every CNTL packet received.
Since APPS only writes on CNTL channel, updation is only needed
for CNTL channel.
Reduce the scope of notifier mutex to reduce the chances of
race condition. Update spelling for few macros.

Change-Id: I0a53ebe0a66660b763d5df1f7084b0f7fa8ebcb0
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>