libceph: nuke bogus encoding version check in osdmap_apply_incremental()

Only version 6 of osdmap encoding is supported, anything other than
version 6 results in an error and halts the decoding process.  Checking
if version is >= 5 is therefore bogus.
Signed-off-by: NIlya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: NAlex Elder <elder@linaro.org>

net/ceph/osdmap.c

@@ -952,11 +952,10 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 		if (err < 0)
 			goto bad;
 	}
-	if (version >= 5) {
-		err = __decode_pool_names(p, end, map);
-		if (err)
-			goto bad;
-	}
+
+	err = __decode_pool_names(p, end, map);
+	if (err)
+		goto bad;
 
 	/* old_pool */
 	ceph_decode_32_safe(p, end, len, e_inval);