arm64: dts: renesas: Factor out White Hawk Single board support

[ Upstream commit d43c077c ]

Move the common parts for the Renesas White Hawk Single board to
white-hawk-single.dtsi, to enable future reuse.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/1661743b18a9ff9fac716f98a663b39fc8488d7e.1733156661.git.geert+renesas@glider.be


Stable-dep-of: 8ffec7d6 ("arm64: dts: renesas: white-hawk-single: Improve Ethernet TSN description")
Signed-off-by: Sasha Levin <sashal@kernel.org>