This adds VP9 decoding for the Amlogic GXL, G12A & SM1 SoCs, using
the commong "HEVC" HW decoder.

For G12A & SM1, it uses the IOMMU support from the firmware.

For 10bit decoding, the firmware can only decode in the proprietary
Amlogic Framebuffer Compression format, but can output in 8bit NV12
buffer while writing the decoded frame.
Signed-off-by: Maxime Jourdan <mjourdan@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>