drm/sun4i: backend: Handle the SAT

The A33 has an block called SAT that is part of the backend that needs to
be clocked and out of reset to be able for the backend to operate properly.

Extend the binding to have the SAT resources listed, and claim them when
the backend probes.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>