Documentation: arm: marvell: Add 88F6825 model into list

88F6825 is just 88F6820 but without encryption acceleration hardware and is
used e.g. in DTS file arch/arm/boot/dts/armada-385-clearfog-gtr.dtsi

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20210814124805.14568-1-pali@kernel.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>