media: mtk-jpeg: Fix null-ptr-deref during unload module

commit 17af2b39daf12870cac61ffc360e62bc35798afb upstream.

The workqueue should be destroyed in mtk_jpeg_core.c since commit
09aea13e ("media: mtk-jpeg: refactor some variables"), otherwise
the below calltrace can be easily triggered.

[  677.862514] Unable to handle kernel paging request at virtual address dfff800000000023
[  677.863633] KASAN: null-ptr-deref in range [0x0000000000000118-0x000000000000011f]
...
[  677.879654] CPU: 6 PID: 1071 Comm: modprobe Tainted: G           O       6.8.12-mtk+gfa1a78e5d24b+ #17
...
[  677.882838] pc : destroy_workqueue+0x3c/0x770
[  677.883413] lr : mtk_jpegdec_destroy_workqueue+0x70/0x88 [mtk_jpeg_dec_hw]
[  677.884314] sp : ffff80008ad974f0
[  677.884744] x29: ffff80008ad974f0 x28: ffff0000d7115580 x27: ffff0000dd691070
[  677.885669] x26: ffff0000dd691408 x25: ffff8000844af3e0 x24: ffff80008ad97690
[  677.886592] x23: ffff0000e051d400 x22: ffff0000dd691010 x21: dfff800000000000
[  677.887515] x20: 0000000000000000 x19: 0000000000000000 x18: ffff800085397ac0
[  677.888438] x17: 0000000000000000 x16: ffff8000801b87c8 x15: 1ffff000115b2e10
[  677.889361] x14: 00000000f1f1f1f1 x13: 0000000000000000 x12: ffff7000115b2e4d
[  677.890285] x11: 1ffff000115b2e4c x10: ffff7000115b2e4c x9 : ffff80000aa43e90
[  677.891208] x8 : 00008fffeea4d1b4 x7 : ffff80008ad97267 x6 : 0000000000000001
[  677.892131] x5 : ffff80008ad97260 x4 : ffff7000115b2e4d x3 : 0000000000000000
[  677.893054] x2 : 0000000000000023 x1 : dfff800000000000 x0 : 0000000000000118
[  677.893977] Call trace:
[  677.894297]  destroy_workqueue+0x3c/0x770
[  677.894826]  mtk_jpegdec_destroy_workqueue+0x70/0x88 [mtk_jpeg_dec_hw]
[  677.895677]  devm_action_release+0x50/0x90
[  677.896211]  release_nodes+0xe8/0x170
[  677.896688]  devres_release_all+0xf8/0x178
[  677.897219]  device_unbind_cleanup+0x24/0x170
[  677.897785]  device_release_driver_internal+0x35c/0x480
[  677.898461]  device_release_driver+0x20/0x38
...
[  677.912665] ---[ end trace 0000000000000000 ]---

Fixes: 09aea13e ("media: mtk-jpeg: refactor some variables")
Cc: <stable@vger.kernel.org>
Signed-off-by: Guoqing Jiang <guoqing.jiang@canonical.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>