media: verisilicon: Move Rockchip hardware drivers to the corresponding option

There is no need to compile the Rockchip specific drivers if
CONFIG_VIDEO_HANTRO_ROCKCHIP is not set.
All the driver functions are only referenced by rockchip_vpu_hw.c which
is already under this option.

Fixes: c9caebd5 ("media: hantro: merge Rockchip platform drivers")
Fixes: c07665f9 ("media: hantro: Add H.264 support for Rockchip VDPU2")
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>