qseecom: Fix issue with incomplete command exiting prematurely

A process waiting on a signal can be awaken by any signals. We
need to only continue processing when the condition of the
wait event is met.

Change-Id: Ib2102babbb505876f89b04399729e6ff5a475605
Signed-off-by: Mona Hossain <mhossain@codeaurora.org>
Signed-off-by: Zhen Kong <zkong@codeaurora.org>