iio: accel: adxl367: Use automated cleanup for locks and iio direct m…

…ode.

Switching to the iio_device_claim_direct_scoped() for state
and to guard() based unlocking of mutexes simplifies error handling
by allowing direct returns when an error is encountered.

Reviewed-by: Nuno Sa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Cameron <[email protected]>