msm: sde: Switch to non-secure at session close

This change adds functionality to switch back to non-secure
state at the close of the secure rotator session. Without this
change the transition is delayed until a non-secure transition is
started.

CRs-Fixed: 1102597
Change-Id: I7f9fab066b8212808273474576884990ac8d8fef
Signed-off-by: Abhijit Kulkarni <kabhijit@codeaurora.org>