renderonly: close the gpu fd when destroying renderonly

renderonly: close the gpu fd when destroying renderonly

Currently the screen destruction closes the dup'ed fd, but not the
original renderonly gpu fd, which is kept around for the lifetime of
the renderonly.

Squashed revert of "vc4: Don't leak the GPU fd for renderonly usage."
(commit 99ef66c325a99b3e191987d8327e7e4cd4aafcd7) as requested by Eric.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6983>