qseecom: Add application access mutex locks

Multiple clients are accessing crypto clock at same isntances, which
makes the clock reference count to unexpected value. Ioctls are mutex
protected to maintain proper clock reference count. Also cleaned-up
some code for kernel clients.

Change-Id: I2509e0e78a4eedd78cf2f37fb7efdf741ac3d50c
Signed-off-by: AnilKumar Chimata <anilc@codeaurora.org>