ACPI: Add support for nargs_prop in acpi_fwnode_get_reference_args()

ACPI: Add support for nargs_prop in acpi_fwnode_get_reference_args()

Currently, ACPI does not support the use of a nargs_prop (e.g.,
associated with a reference in fwnode_property_get_reference_args().
Instead, ACPI expects the number of arguments (nargs) to be explicitly
passed or known.

This behavior diverges from Open Firmware (OF), which allows the use of
a #*-cells property in the referenced node to determine the number of
arguments. Since fwnode_property_get_reference_args() is a common
interface used across both OF and ACPI firmware paradigms, it is
desirable to have a unified calling convention that works seamlessly for
both.

Add the support for ACPI to parse a nargs_prop from the referenced
fwnode, aligning its behavior with the OF backend. This allows drivers
and subsystems using fwnode_property_get_reference_args() to work in a
firmware-agnostic way without having to hardcode or special-case
argument counts for ACPI.

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
Link: https://lore.kernel.org/r/20250818040920.272664-16-apatel@ventanamicro.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>