config: remove HAVE_VFS_ITERATE/HAVE_VFS_ITERATE_SHARED

Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes #16479

module/os/linux/zfs/zfs_vnops_os.c

@@ -1507,7 +1507,7 @@ out:
  * we use the offset 2 for the '.zfs' directory.
  */
 int
-zfs_readdir(struct inode *ip, zpl_dir_context_t *ctx, cred_t *cr)
+zfs_readdir(struct inode *ip, struct dir_context *ctx, cred_t *cr)
 {
 	(void) cr;
 	znode_t		*zp = ITOZ(ip);
@@ -1613,7 +1613,7 @@ zfs_readdir(struct inode *ip, zpl_dir_context_t *ctx, cred_t *cr)
 			type = ZFS_DIRENT_TYPE(zap.za_first_integer);
 		}
 
-		done = !zpl_dir_emit(ctx, zap.za_name, strlen(zap.za_name),
+		done = !dir_emit(ctx, zap.za_name, strlen(zap.za_name),
 		    objnum, type);
 		if (done)
 			break;