qseecom: Free ion memory even if keymaster app is not unloaded

Make a change to free the ion memory allocated for keymaster client
even if keymaster app doesn't need to be unloaded from TZ, so as to
avoid memory leak.

CRs-Fixed: 724638
Change-Id: I3ddb68c8a3f96b0a44afc3efc63e93f0a8be51bb
Signed-off-by: Zhen Kong <zkong@codeaurora.org>