dt-bindings: memory: Add entry for version 3.80a

Add an entry for version 3.80a of the Synopsys DDR controller.

Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lkml.kernel.org/r/20211012190709.1504152-4-dinguyen@kernel.org