drm: Clear state->acquire_ctx before leaving drm_atomic_helper_commit_duplicated_state()

[ Upstream commit aa394b0d ]

drm_atomic_helper_commit_duplicated_state() sets state->acquire_ctx to
the context given in the argument and leaves it in state after it
quits. The lifetime of state and context are not guaranteed to be the
same, so we shouldn't leave that pointer hanging around. This patch
resets the context to NULL to avoid any oopses.

Changes in v2:
- Added to the set

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181129150423.239081-1-sean@poorly.run


Signed-off-by: Sasha Levin <sashal@kernel.org>