diag: Add concurrency protection to writes on smd data channels

Currently, diag does not protect against multiple threads writing
on a diag smd data channel at the same time. Make changes to protect
against concurrent writes on the same smd data channel.

Change-Id: I80982175821d60ffbc6bc4d6058c322dd894ebd3
Signed-off-by: Dixon Peterson <dixonp@codeaurora.org>
2 files changed