qseecom: fix an issue related to search app when unloading an app

Make a change in qseecom_unload_app to stop the execution of app
searching when an app is founded, even if this app is in use with
ref_cnt greater than one.

Change-Id: I0328252668ef1069ec514bfb913b927a7da76594
Signed-off-by: Zhen Kong <zkong@codeaurora.org>
Signed-off-by: William Clark <wclark@codeaurora.org>