libceph: fix wrong name "Ceph filesystem for Linux"

modinfo libceph prints the module name "Ceph filesystem for Linux",
which is same as the real fs module ceph. It's confusing.
Signed-off-by: Hong Zhiguo <zhiguohong@tencent.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

net/ceph/ceph_common.c

@@ -741,5 +741,5 @@ module_exit(exit_ceph_lib);
 MODULE_AUTHOR("Sage Weil <sage@newdream.net>");
 MODULE_AUTHOR("Yehuda Sadeh <yehuda@hq.newdream.net>");
 MODULE_AUTHOR("Patience Warnick <patience@newdream.net>");
-MODULE_DESCRIPTION("Ceph filesystem for Linux");
+MODULE_DESCRIPTION("Ceph core library");
 MODULE_LICENSE("GPL");