arm64: dts: renesas: Update Ebisu and Draak bootargs

Update Ebisu and Draak bootargs to match other boards

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>