ceph::conf: add more performant mkfs/mount parameter for xfs

We did a lot of testing to resolve performance issues with
ceph on XFS. The changed mkfs.xfs and mount parameter result
in a better XFS/ceph performance for us so far. We may will
change these options later based on more performance tests.

Feature: SMBCAP-3475

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>