device: deprecate (z_)device_usable_check

The functionality provided by device_usable_check is already provided by
device_is_ready. The (z_)device_usable_check APIs have been
re-implemented using the (z_)device_is_ready APIs and have been marked
as deprecated.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>