ARM: shmobile: bockw dts: Update console parameters

Drop the "console=" parameter from the kernel command line, as it's no
longer needed for DT-based platforms.
Add serial port config to chosen/stdout-path.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>