iio: accel: bmc150: Removed unused bmc150_accel_dat irq member

The bmc150_accel_dat struct irq member is only ever used inside
bmc150_accel_core_probe, drop it and just use the function argument
directly.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20201130141954.339805-1-hdegoede@redhat.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>