libceph: support CEPH_FEATURE_OSD_CACHEPOOL feature

Announce our (limited, see previous commit) support for CACHEPOOL
feature.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
diff --git a/include/linux/ceph/ceph_features.h b/include/linux/ceph/ceph_features.h
index d21b34d..138448f 100644
--- a/include/linux/ceph/ceph_features.h
+++ b/include/linux/ceph/ceph_features.h
@@ -80,6 +80,7 @@
 	 CEPH_FEATURE_CRUSH_TUNABLES2 |		\
 	 CEPH_FEATURE_REPLY_CREATE_INODE |	\
 	 CEPH_FEATURE_OSDHASHPSPOOL |		\
+	 CEPH_FEATURE_OSD_CACHEPOOL |		\
 	 CEPH_FEATURE_CRUSH_V2 |		\
 	 CEPH_FEATURE_EXPORT_PEER)