xfs_repair: set args.geo in dir2_kill_block

xfs_repair: set args.geo in dir2_kill_block

This path in xfs_repair:

dir2_kill_block
	libxfs_da_shrink_inode
		xfs_dir2_shrink_inode
			xfs_dir2_db_to_da

segfaults, because dir2_kill_block() does not initialize
args.geo, and a null geometry winds up in xfs_dir2_db_to_da(),
which dereferences it.

Fix that.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>