ceph-disk: fix regression in cciss devices names

ceph-disk: fix regression in cciss devices names

The cciss driver has device paths such as /dev/cciss/c0d1 with a
matching /sys/block/cciss!c0d1. The general case is that whenever a
device name is found in /sys/block, the / is replaced by the !.

When refactoring the ceph-disk list subcommand, this conversion was
overlooked in a few places. All explicit concatenation of /dev with a
device name are replaced with a call to get_dev_name which does the same
but also converts all ! in /.

http://tracker.ceph.com/issues/13970 Fixes: #13970

Signed-off-by: Loic Dachary <loic@dachary.org>