xfs: move comment about two 2 keys per pointer in the rmap btree

Move it to the relevant initialization of the ops structure instead
of a place that has nothing to do with the key size.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

fs/xfs/libxfs/xfs_rmap_btree.c

@@ -477,6 +477,7 @@ const struct xfs_btree_ops xfs_rmapbt_ops = {
 	.geom_flags		= XFS_BTGEO_OVERLAPPING,
 
 	.rec_len		= sizeof(struct xfs_rmap_rec),
+	/* Overlapping btree; 2 keys per pointer. */
 	.key_len		= 2 * sizeof(struct xfs_rmap_key),
 	.ptr_len		= XFS_BTREE_SHORT_PTR_LEN,
 
@@ -509,7 +510,6 @@ xfs_rmapbt_init_common(
 {
 	struct xfs_btree_cur	*cur;
 
-	/* Overlapping btree; 2 keys per pointer. */
 	cur = xfs_btree_alloc_cursor(mp, tp, XFS_BTNUM_RMAP, &xfs_rmapbt_ops,
 			mp->m_rmap_maxlevels, xfs_rmapbt_cur_cache);
 	cur->bc_ag.pag = xfs_perag_hold(pag);