ARM: dts: socfpga: use stdout-path for chosen node

Use stdout-path dts property for kernel console.

There were two socfpga boards left not using stdout-path:
socrates and vining. Make sure they match the other boards.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>