media: rockchip/vpu: Rename pixel format helpers

The rockchip VPU driver uses generic names for its pixel format
helpers. We want to use the same names for generic versions
of these helpers, so rename the rockchip ones.

The driver will be switched to the generic helpers later.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>