ARM: dts: vfxxx: Add syscon compatible with OCOTP

Add syscon compatibility with Vybrid OCOTP node. This is required to
access the UID.

Fixes: fa8d20c8

 ("ARM: dts: vfxxx: Add node corresponding to OCOTP")
Cc: stable@vger.kernel.org
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Chris Healy <cphealy@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>