iio: imu: adis16475: drop ifdef around CONFIG_DEBUG_FS

Use IS_ENABLED(CONFIG_DEBUG_FS) to return early in case debugfs is not
present. Since this is known at compile time, it allows the compiler to
drop any unused code. Therefore no need to wrap the code with #ifdef.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://patch.msgid.link/20240809-dev-adis-debugfs-improv-v1-1-d3adb6996518@analog.com


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