Allwinner a83t has a 1 KB sid block with efuse for security rootkey and thermal
calibration data, add node to describe it.

a83t-sid is not currently supported by nvmem/sunxi-sid, but it is
supported in an external driver for FreeBSD.
Signed-off-by: NKyle Evans <kevans@FreeBSD.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@bootlin.com>