ARM: dts: meson8b: use the existing wdt node to override the compatible

Meson8b has to define it's own compatible string for the watchdog. This
patch removes the duplicate resource (register region and interrupt)
definition from meson8b.dtsi and simply re-uses these values from
meson.dtsi (as the register offset, size and interrupt are identical).

This is purely cosmetic and does not change any functionality.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>