panfrost: Revert "Disable frame throttling"

panfrost: Revert "Disable frame throttling"

This reverts commit 4fee7b30c0ecc56d7659ecad1d8b140ab253f0db, which was
intended to be a temporary workaround for a leak introduced in
a65e29ccb26 ("gallium: simplify throttle implementation"). However, that
leak was then fixed in 023282a4f667695ea1dbbe9fbe1cd3a9d550a426 and we
forgot to revert this hack.

Closes: #2108
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Cc: mesa-stable
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5858>