Revert "drm/amd/display: Enable fast plane updates when state->allow_modeset = true"

This reverts commit ebc8c6f18322ad54275997a888ca1731d74b711f.

There are still missing corner cases with cursor interaction and these
fast plane updates on Picasso and Raven2 leading to endless PSTATE
warnings for typical desktop usage depending on the userspace.

This change should be reverted until these issues have been resolved.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110949


Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: David Francis <david.francis@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>