Use provided uid/gid for setattr

When changing the uid/gid of a file via zfs_setattr() use the
Posix id passed in iattr->ia_uid/gid.  While the zfs_fuid_create()
code already had the fuid support disabled for Linux it was
returning the uid/gid from the credential.  With this change
the 'chown' command which relies on setxattr is now working
properly.

Also remove a little stray white space which was in front of
zfs_update_inode() call and the end of zfs_setattr().

module/zfs/zfs_fuid.c

@@ -639,10 +639,10 @@ zfs_fuid_create(zfs_sb_t *zsb, uint64_t id, cred_t *cr,
 	}
 	return (FUID_ENCODE(idx, rid));
 #else
-	if (type == ZFS_OWNER)
-		return crgetuid(cr);
-	else
-		return crgetgid(cr);
+	/*
+	 * The Linux port only supports POSIX IDs, use the passed id.
+	 */
+	return (id);
 #endif
 }