soc: amlogic: add meson-canvas driver

Amlogic SoCs have a repository of 256 canvas which they use to
describe pixel buffers.

They contain metadata like width, height, block mode, endianness [..]

Many IPs within those SoCs like vdec/vpu rely on those canvas to read/write
pixels.

Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Tested-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Maxime Jourdan <mjourdan@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>