qseecom: decrease clk_access_cnt

When scm_call returns EBUSY and app_access_lock is released,
clk_access_cnt could be larger than 2 as a new qseecom thread
may come to increase clk_access_cnt in this situation. So
clk_access_cnt should be always decreased.

Change-Id: I2400e807b9f15e3d7d8caad6978bfa93aa3cdd76
Signed-off-by: Zhen Kong <zkong@codeaurora.org>