platform/x86: wmi: Simplify get_subobj_info()

All callers who call get_subobj_info() with **info being NULL
should better use acpi_has_method() instead.
Convert the only caller who does this to acpi_has_method()
to drop the dummy info handling.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20231218192420.305411-7-W_Armin@gmx.de


Signed-off-by: Hans de Goede <hdegoede@redhat.com>