drm/sun4i: mixer: Add quirk for number of VI scalers

drm/sun4i: mixer: Add quirk for number of VI scalers

On DE2 and DE3, UI scalers are located right after VI scalers. So in
order to calculate proper UI scaler base address, number of VI scalers
must be known. In practice, it is same as number of VI channels, but it
doesn't need to be.

Let's make a quirk for this number. Code for configuring channels and
associated functions won't have access to vi_num quirk anymore after
rework for independent planes.

Reviewed-by: Chen-Yu Tsai <wens@kernel.org>
Tested-by: Ryan Walklin <ryan@testtoast.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://patch.msgid.link/20251104180942.61538-27-jernej.skrabec@gmail.com
Signed-off-by: Chen-Yu Tsai <wens@kernel.org>