ARM: dts: vf610-zii-dev-rev-b: change switch2 label

Rename the switch2@0 label of the switch2 node to switch@0 to respect
the general unit@address DTS rule, and be consistent with the other
switch nodes of the DTS file.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>