Add a stdout-path property so that automatic console selection works
in the absence of a "console=" parameter on the kernel command line.

Note that we have to keep the "console=ttySC0,38400" parameter in
chosen/bootargs, else the console will use the default setting of 115200
baud.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>