media: sun8i-di: Fix chroma difference threshold

[ Upstream commit 856525e8 ]

While there is no good explanation what this value does, vendor driver
uses value 31 for it. Align driver with it.

Fixes: a4260ea4 ("media: sun4i: Add H3 deinterlace driver")
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>