NFS: Remove the NIPQUAD from nfs_try_mount

In the name of address family compatibility, we can't have the NIP_FMT and
NIPQUAD macros in nfs_try_mount().  Instead, we can make use of an unused
mount option to display the mount server's hostname.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: Aurelien Charbon <aurelien.charbon@ext.bull.net>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>