media: hantro: Fix media device bus_info string

Even if model and bus_info currently both are 32 bytes large, use
the correct array size for bus_info.

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>