FROMGIT: drm: writeback: Fix use after free in drm_writeback_connector_cleanup()

The drm_writeback_cleanup_job() function frees "pos" so call
list_del(&pos->list_entry) first to avoid a use after free.

Fixes: 1914ba2b ("drm: writeback: Create drmm variants for drm_writeback_connector initialization")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/78abd541-71e9-4b3b-a05d-2c7caf8d5b2f@stanley.mountain


Signed-off-by: Maxime Ripard <mripard@kernel.org>
(cherry picked from commit ff3881cc
 https://anongit.freedesktop.org/git/drm/drm-misc.git

 drm-misc-next)

Fixes: 8d550a8f ("FROMGIT: drm: writeback: Create drmm variants for
drm_writeback_connector initialization")

Bug: 414366730
Test: atest VtsHalGraphicsComposer3_TargetTest

Change-Id: I889a42e9651a41e7f98f4f9daa00796b896bdc8d
Signed-off-by: Paz Zcharya <pazz@google.com>