diag: Remove spinlock protection while releasing wake source

Currently, apps diag is holding a spinlock while releasing
wake source. This may lead to spinlock contention in case
multiple zero size packets are received over smd thus leading
to lockout. This patch removes the spinlock protection while
releasing wake source.

Change-Id: I73f2b6f584bfbc259cd534c59aedbacd4cc59381
Signed-off-by: Katish Paran <kparan@codeaurora.org>