trace: ipc_logging: Fix potential dead in ipc_log_write

Fix potential deadlock by unlocking spinlock when returning
from an error case during ipc_log_write.

CRs-Fixed: 2059308
Change-Id: If253470d720af1b42f9ebcfb98d69d4c65ab73bc
Signed-off-by: Chris Lew <clew@codeaurora.org>