NFS: Pass mntfh as part of the nfs_mount_info structure

This allows me to use the filehandle allocated in nfs_fs_mount() for nfs
v4 mounts instead of allocating a new one.  Rather than change
nfs4_mount() to look almost exactly like nfs_fs_mount(), I instead
remove the function.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>