ARM: dts: vf-colibri: add CAN support

Add Colibri standard pinmux for FlexCAN controller instances. CAN
is not a standard Colibri feature, but the datasheet predefines
pins which provide CAN (compatible across some modules). Hence,
add the pinmux on module level.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>