dist/common/scripts/scylla_setup: do not ask to select disks when there's no free disk
dist/common/scripts/scylla_setup: do not ask to select disks when there's no free disk

When there's no free disk, it asks to select disks from empty list:

"Please select disks from following list:
type 'done' to finish selection. selected:"

We should avoid to ask it, abort RAID setup instead.

Fixes #1673

Signed-off-by: Takuya ASADA <4ebfb6f510af412d6e89fefa3ab96d9c8b5e3fff@scylladb.com>
Message-Id: <1474429218-28382-1-git-send-email-4ebfb6f510af412d6e89fefa3ab96d9c8b5e3fff@scylladb.com>

avikivity/scylla,duarten/scylla,duarten/scylla,raphaelsc/scylla,raphaelsc/scylla,scylladb/scylla,avikivity/scylla,raphaelsc/scylla,duarten/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla