msm: kgsl: Mark the scratch buffer as privileged

Mark the scratch buffer as privileged so that it can only be accessed by
GPU through the ringbuffer. To accomplish this, we need to:

1. Disable the shadow rptr feature.
2. Trigger RPTR update from GPU using a WHERE_AM_I packet.
3. Add support for the new ucode.

Change-Id: I9b388f55f53b69028b9bbb2306cb43fd1297c52f
Signed-off-by: Akhil P Oommen <akhilpo@codeaurora.org>
Signed-off-by: Pranav Patel <pranavp@codeaurora.org>