media: rkvdec: increase max supported height for H.264

After testing it is possible for the hardware to decode H264
bistream with a height up to 2560.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Fixes: cd33c830 ("media: rkvdec: Add the rkvdec driver")
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>