msm: kgsl: Add a property to find if secure context is supported

Add a property to determine if a target support secure context
for use cases like CPZ.

This property can be used by userspace application to create
a secure context if its supported on the target.

Change-Id: I1ccc824378fb8fbd2cfbc7b811c6c3fdcd17803e
Signed-off-by: Sunil Khatri <sunilkh@codeaurora.org>