dt-bindings: sram: sunxi: Add compatible for the H6 SRAM C1

This introduces a new compatible for the H6 SRAM C1 section, that is
compatible with the SRAM C1 section as found on the A10.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>