'#interrupt-cells' is a required provided for interrupt providers,
hence make it required.

While at it, move '#interrupt-cells' in the example to match common sort
order.

Fixes: 361104b0 ("dt-bindings: mfd: Convert da9063 to yaml")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/f512045738d2102c771a171a514ed7cf612c6d6f.1708944455.git.geert+renesas@glider.beSigned-off-by: Lee Jones <lee@kernel.org>