arm64: dts: allwinner: a64: Add support for the SRAM C1 section

Add the description for the SRAM C1 section to the A64 device-tree.

Since there is no entry for this section in the A64 manual, the base
address and size were only verified to be consistent empirically.

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>