arm64: dts: exynos: Include common syscon restart/poweroff for Exynos7

arm64: dts: exynos: Include common syscon restart/poweroff for Exynos7

Exynos7 uses the same syscon reboot and poweroff nodes as other Exynos
SoCs, so instead of duplicating code we can just include common dtsi
file, which already contains definitions of them. After this change,
poweroff node will be also available, previously this dts file did
contain only reboot node.

Fixes: fb026cb65247 ("arm64: dts: Add reboot node for exynos7")
Fixes: b9024cbc937d ("arm64: dts: Add initial device tree support for exynos7")
Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Link: https://lore.kernel.org/r/20201107133926.37187-1-pawel.mikolaj.chmiel@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>