ceph-volume: drop is_locked_raw_device()

ceph-volume: drop is_locked_raw_device()

This functions works for what it is supposed to do:

check if a device is busy.

That being said, this induces a race condition in `get_devices()`

Indeed, it does:

1/ `os.open()` with `(os.O_RDWR | os.O_EXCL)`
2/ `os.close()`

The second call has an effect: it triggers a udev event which causes
systemd-udevd to re-process the device. This seems to be a question of
millisecond but because of this, /sys (sysfs) isn't fully populated as
expected. Given that get_devices() collects a lot of details from sysfs
in a loop, some of these details can be missed.

ceph-volume overall doesn't make decisions based on `is_locked_raw_device()`
This detail is used only for reporting (inventory).
For this reason, dropping this function seems reasonnable.
As a compromise, we can check if the device has partitions and/or a FileSystem
on it.

Signed-off-by: Guillaume Abrioux <gabrioux@ibm.com>
(cherry picked from commit 2422ad867dff9d526d7e8be543178c897991097f)