Do not allow the user to manually set compress_level

It is set atomically as part of setting `compress` when the
compression type supports multiple levels.

Signed-off-by: Allan Jude <allan@klarasystems.com>

Author: allanjude

module/zfs/zfs_ioctl.c

@@ -4582,6 +4582,10 @@ zfs_check_settable(const char *dsname, nvpair_t *pair, cred_t *cr)
 		}
 		break;
 
+	case ZFS_PROP_COMPRESS_LEVEL:
+		return (SET_ERROR(EINVAL));
+		break;
+
 	case ZFS_PROP_COPIES:
 		if (zfs_earlier_version(dsname, SPA_VERSION_DITTO_BLOCKS))
 			return (SET_ERROR(ENOTSUP));