Revert "Use directory xattrs for symlinks"

This reverts commit 6a7c0cc.

A proper fix for Issue openzfs#1648 was landed under Issue openzfs#1890, so this is no
longer needed.

Signed-off-by: Ned Bass <bass6@llnl.gov>

module/zfs/zpl_xattr.c

@@ -446,10 +446,6 @@ zpl_xattr_set_sa(struct inode *ip, const char *name, const void *value,
 		if (error == -ENOENT)
 			error = zpl_xattr_set_dir(ip, name, NULL, 0, flags, cr);
 	} else {
-		/* Do not allow SA xattrs in symlinks (issue #1648) */
-		if (S_ISLNK(ip->i_mode))
-			return (-EMLINK);
-
 		/* Limited to 32k to keep nvpair memory allocations small */
 		if (size > DXATTR_MAX_ENTRY_SIZE)
 			return (-EFBIG);