media: dt-bindings: media: nxp, imx8mq-vpu: Split G1 and G2 nodes

The G1 and G2 are independent and separate decoder blocks
that are enabled by the vpu-blk-ctrl power-domain controller,
which now has a proper driver.

Because these blocks only share the power-domain, and can be
independently fused out, update the bindings to support separate
nodes for the G1 and G2 decoders with vpu-blk-ctrl power-domain
support.

The new DT + old kernel isn't a supported configuration.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>