arm64: dts: renesas: ebisu: Add serial console pins

This patch adds pin control for SCIF2 on R8A77990 E3 Ebisu.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>