iio: accel: bmc150: Move check for second ACPI device into a separate function

Move the check for a second ACPI device for BOSC0200 ACPI fwnodes into
a new bmc150_acpi_dual_accel_probe() helper function.

This is a preparation patch for adding support for a new "DUAL250E" ACPI
Hardware-ID (HID) used on some devices.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210523170103.176958-4-hdegoede@redhat.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>