msm: bam_dmux: reduce notify_all() logging

Notify_all() logs a message to the internal log for each client that gets
notified.  This consumes a lot of log space for little real information.

Reduce the logging to a single statement indicating when and why
notify_all() was called.  It can be safely assumed that every valid
client will be notified when notify_all() is called.

Change-Id: I5ae6ea72a734e37dce05539e2de3108ed5b2b40d
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>