arm64: dts: meson-sm1-sei610: add stdout-path property back

The commit d4609acce187 ("arm64: dts: meson-sm1-sei610: enable DVFS")
incorrectly removed the chosen node and the stdout-path property.

Add these back.

Fixes: d4609acce187 ("arm64: dts: meson-sm1-sei610: enable DVFS")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>