xfs_spaceman: embed struct xfs_fd in struct fileio

xfs_spaceman: embed struct xfs_fd in struct fileio

Replace the open-coded fd and geometry fields of struct fileio with a
single xfs_fd, which will enable us to use it natively throughout
xfs_spaceman in upcoming patches.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>