ARM: shmobile: koelsch dts: Drop console= bootargs parameter

Koelsch is now restricted to booting from DT, so chosen/stdout-path is
always used, and we can drop the "console=" parameter from chosen/bootargs.

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