Will cause below warning then reboot when exercising the decoder with
fluster on mt8192-asurada-spherion.

This deinit function is called on the v4l2 release callback, even though
the work might not have been initialized as that only happens if/when the
codec specific 'decode' callback is called (as a result of device_run m2m
callback).

CPU: 5 PID: 2338 Comm: gst-launch-1.0 Tainted: G        W          6.4.0-rc5-next-20230607+ #475
Hardware name: Google Spherion (rev0 - 3) (DT)
pstate: 00400009 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __flush_work.isra.0+0x23c/0x258
lr : __cancel_work_timer+0x14c/0x1c8
sp : ffff8000896e3b00
x29: ffff8000896e3b00 x28: ffff57c3d4079f80 x27: 0000000000000000
x26: ffff57c3d4079f80 x25: ffffb76395b59dc8 x24: 0000000000000001
x23: ffffb763928daab8 x22: ffff57c3d4079f80 x21: 0000000000000000
x20: ffffb763955f6778 x19: ffff57c3cf06f4a0 x18: 0000000000000000
x17: 000000040044ffff x16: 005000f2b5503510 x15: 0000000000000000
x14: ffff57c3c03a1f80 x13: ffffa0616a2fc000 x12: 000000003464d91d
x11: 0000000000000000 x10: 0000000000001b10 x9 : ffffb763928de61c
x8 : ffff57c3d407baf0 x7 : 0000000000000000 x6 : ffff57c3d4079f80
x5 : ffff57c3d4079f80 x4 : 0000000000000000 x3 : 0000000000000000
x2 : ffff8000896e3bf0 x1 : 0000000000000011 x0 : 0000000000000000
Call trace:
 __flush_work.isra.0+0x23c/0x258
 __cancel_work_timer+0x14c/0x1c8
 cancel_work_sync+0x1c/0x30
 vdec_msg_queue_deinit+0xac/0xc8
 vdec_h264_slice_deinit+0x64/0xb8
 vdec_if_deinit+0x3c/0x68
 mtk_vcodec_dec_release+0x20/0x40
 fops_vcodec_release+0x50/0xd8
 v4l2_release+0x7c/0x100
 __fput+0x80/0x270
 ____fput+0x18/0x30
 task_work_run+0x78/0xe0
 do_notify_resume+0x29c/0x7f8
 el0_svc+0xa4/0xb8
 el0t_64_sync_handler+0xc0/0xc8
 el0t_64_sync+0x1a8/0x1b0
---[ end trace 0000000000000000 ]---

Fixes: 297160d4 ("media: mediatek: vcodec: move core context from device to each instance")
Reported-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>