drm/msm: Disable the RPTR shadow

[ Upstream commit f6828e0c4045f03f9cf2df6c2a768102641183f4 ]

Disable the RPTR shadow across all targets. It will be selectively
re-enabled later for targets that need it.

Cc: stable@vger.kernel.org
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>