iio: imu: st_lsm6dsx: Remove useless dev_fwnode() calls

The device property APIs designed that way that they will return an error when
there is no valid fwnode provided. Moreover, the check for NULL of dev_fwnode()
is not fully correct as in some (currently rare) cases it may contain an error
pointer. This is not a problem anyway (see keyword 'valid' above) that's why
the code works properly even without this change.

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://patch.msgid.link/20240826212344.866928-3-andy.shevchenko@gmail.com


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