bus: simple-pm-bus: Probe the Layerscape SCFG node

bus: simple-pm-bus: Probe the Layerscape SCFG node

Make the simple-pm-bus driver probe the Layerscape SCFG dt nodes and
populate platform_device structures from its child dt nodes.

This is now needed because its child interrupt-controller - ls-extirq -
is being handled as a platform_device instead of being initialized
through the IRQCHIP_DECLARE infrastructure which impeded its parent IRQ
retrieval through the blamed commit.

Note that this does not set ONLY_BUS because that enables the
of_platform_populate() call. The extra power management operations which
are enabled by that are not required but harmless.

Fixes: 1b1f04d8271e ("of/irq: Ignore interrupt parent for nodes without interrupts")
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260122134034.3274053-3-ioana.ciornei@nxp.com