drm/msm: Deprecate MSM_BO_UNCACHED harder

Handle the demotion to MSM_BO_WC at the userspace ABI level, and fix
the remaining internal MSM_BO_UNCACHED user.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/489339/
Link: https://lore.kernel.org/r/20220613194623.2588353-1-robdclark@gmail.com