We got the following warning when booting the kernel:

[    3.243674] INFO: trying to register non-static key.
[    3.243922] The code is fine but needs lockdep annotation, or maybe
[    3.244230] you didn't initialize this object before use?
[    3.245642] Call Trace:
[    3.247836]  lock_acquire+0xff/0x2d0
[    3.248727]  tw686x_audio_irq+0x1a5/0xcc0 [tw686x]
[    3.249211]  tw686x_irq+0x1f9/0x480 [tw686x]

The lock 'vc->qlock' will be initialized in tw686x_video_init(), but the
driver registers the irq before calling the tw686x_video_init(), and we
got the warning.

Fix this by registering the irq at the end of probe

Fixes: 704a84cc ("[media] media: Support Intersil/Techwell TW686x-based video capture cards")
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>