libxfs: pass IGET flags through to xfs_iread

libxfs: pass IGET flags through to xfs_iread

Change the lock_flags parameter to iget_flags so that we can supply
XFS_IGET_ flags in future patches.  All callers of libxfs_iget and
libxfs_trans_iget pass zero for this parameter and there are no inode
locks in xfsprogs, so there's no behavior change here.

Port the kernel's version of the xfs_inode_from_disk callsite.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>