[media] Revert "[media] tw5864: remove double irq lock code"

This reverts commit 617e901a ("[media] tw5864: remove double irq lock code").

That commit was rejected by Andrey Utkin <andrey_utkin@fastmail.com>,
but it had already been merged. Revert and apply Andrey's corrected
patch next.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>