dt-bindings: gpio: ep9301: Add missing "#interrupt-cells" to examples

Enabling dtc interrupt_provider check reveals the examples are missing
the "#interrupt-cells" property as it is a dependency of
"interrupt-controller".

Some of the indentation is off, so fix that too.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Nikita Shubin <nikita.shubin@maquefel.me>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>