media: hantro: Remove now unused H264 pic_size

pic_size in hantro_h264_dec_hw_ctx struct is no longer used,
lets remove it.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>