libxfs: use opstate flags and functions for libxfs mount options

libxfs: use opstate flags and functions for libxfs mount options

Port the three LIBXFS_MOUNT flags that actually do anything to set
opstate flags in preparation for removing m_flags in a later patch.
Retain the LIBXFS_MOUNT #defines so that libxfs clients can pass them
into libxfs_mount.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
[sandeen: drop now-unused flags arg from rtmount_init]
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>