media: cedrus: h264: Fix neighbour info buffer size

According to BSP library source, H264 neighbour info buffer size needs
to be 32 kiB for H6. This is similar to H265 decoding, which also needs
double buffer size in comparison to older Cedrus core generations.

Increase buffer size to cover H6 needs. Since increase is not that big
in absolute numbers, it doesn't make sense to complicate logic for older
generations.

Issue was discovered using iommu and cross checked with BSP library
source.

Fixes: 6eb9b758 ("media: cedrus: Add H264 decoding support")
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>