lxd/storage/drivers: Pass mountPath to xfs_growfs
lxd/storage/drivers: Pass mountPath to xfs_growfs

As the man page suggests, xfs_growfs should take the mount point, not
the dev path.

Signed-off-by: Thomas Hipp <5f82c492b3b00e427412d216ce820707a10c51ce@canonical.com>

Skarlso/lxd,lxc/lxd,lxc/lxd,hallyn/lxd,stgraber/lxd,hallyn/lxd,atxwebs/lxd,stgraber/lxd,hallyn/lxd,lxc/lxd,Skarlso/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,Skarlso/lxd,stgraber/lxd,atxwebs/lxd,lxc/lxd,stgraber/lxd,atxwebs/lxd,hallyn/lxd,stgraber/lxd,mjeanson/lxd,stgraber/lxd,hallyn/lxd,mjeanson/lxd,atxwebs/lxd,lxc/lxd,mjeanson/lxd,Skarlso/lxd,hallyn/lxd