ARM: dts: kzm9d: Update console parameters

Add a "serial1" alias for the serial console (it is labeled "uart1").
Add the serial port config to "chosen/stdout-path", which requires
referring to the port by alias.
Drop the "console=" parameter from the kernel command line, as it's no
longer needed for DT-based platforms.

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