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

Documentation/arm/marvell.rst

@@ -140,6 +140,7 @@ EBU Armada family
 	- 88F6821 Armada 382
 	- 88F6W21 Armada 383
 	- 88F6820 Armada 385
+	- 88F6825
 	- 88F6828 Armada 388
 
     - Product infos:   https://web.archive.org/web/20181006144616/http://www.marvell.com/embedded-processors/armada-38x/