arm64: dts: allwinner: h5: Add system-control node with SRAM C1

Add the H5-specific system control node description to its device-tree
with support for the SRAM C1 section, that will be used by the video
codec node later on.

The CPU-side SRAM address was obtained empirically while the size was
taken from the documentation. They may not be entirely accurate.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>