ipc_logging: Allow logging to resume after device suspend

IPC log collection from userspace cannot resume after the
device is put into suspend mode, because 0 is returned to
userspace when this happens and is interpreted as EOF
(end-of-file).

Allow the signal generated during a suspend to be
propagated back to the userspace application, rather than
returning 0, so log collection can be resumed after a
suspend.

CRs-Fixed: 670289
Change-Id: I67cc4cc980d35bbdc3cbc521a3dd0c347be4abf4
Signed-off-by: Steven Cahail <scahail@codeaurora.org>