dt-bindings: mfd: pm8008: Clean up example node names

Devicetree node names should be generic; fix up the pm8008 binding
example accordingly.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231206111754.7410-5-johan+linaro@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>