[XFS] make xfs_ino_t an unsigned long long

Currently xfs_ino_t is defined as a u64 which can either be an unsigned
long long or on some 64 bit platforms and unsigned long.  Just making
it and unsigned long long mean's it's still always 64 bits wide, but we
don't need to resort to cases to print it.

Fixes a warning regression on 64 bit powerpc in current git.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>