qseecom: make change for unload TA

When unloading a TA, the operations to check ref_cnt,
scm_call to unload TA, free app list entry should be
within one critical section. Otherwise, if another
thread comes in and tries to load TA, TA status will
be out-of-sync. so move __qseecom_cleanup_app()
and __qseecom_reentrancy_check_if_no_app_blocked()
to the beginning of qseecom_unload_app(), as these
functions may release app_access mutex for a short
period.

Change-Id: I3e961f4fe1728a32314a3acf7af719374c90d01f
Signed-off-by: Zhen Kong <zkong@codeaurora.org>