passing -n ftype=1 to mkfs.xfs for overlay2 docker storage driver support

[ravilr]

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/7.2_Release_Notes/technology-preview-file_systems.html

says that xfs file systems must be created with the -n ftype=1 option enabled for use as an overlay. Also, dockerd seems to have a check for this as without this, certain docker operations might misbehave.

Can d-s-s create xfs with -n ftype=1 while creating fs for the container fs volume.

@rhatdan @rhvgoyal

[rhvgoyal]

@ravilr Though now latest xfsprogs has been modified so that by default mkfs.xfs uses ftype=1. But I guess it still makes sense to make use of it explicitly just in case user is using newer docker-storage-setup on older distribution.

[rhvgoyal]

@shishir-a412ed Would you like to create a PR for this.