arm64: dts: renesas: r8a77990: Add SCIF-{0,1,3,4,5} device nodes

This patch adds the device nodes for SCIF-{0,1,3,4,5} serial ports to
the R8A77990 SoC.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>