hmm_range_fault related fixes and legacy API removal v3

[Christoph Hellwig]

Hi Jérôme, Ben, Felxi and Jason,

below is a series against the hmm tree which cleans up various minor
bits and allows HMM_MIRROR to be built on all architectures.

Diffstat:

    7 files changed, 81 insertions(+), 171 deletions(-)

A git tree is also available at:

    git://git.infradead.org/users/hch/misc.git hmm-cleanups

Gitweb:

    http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/hmm-cleanups