media: rockchip/vpu: rename from rockchip to hantro

Rename the driver and all relevant identifiers from Rockchip to Hantro,
as other Hantro IP based VPU implementations can be supported by the
same driver.
The RK3288 decoder is Hantro G1 based, the encoder is Hantro H1.

This patch just renames, no functional changes.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>