libceph, ceph: disambiguate ceph_connection_operations handlers

Since a few years, kernel addresses are no longer included in oops
dumps, at least on x86.  All we get is a symbol name with offset and
size.

This is a problem for ceph_connection_operations handlers, especially
con->ops->dispatch().  All three handlers have the same name and there
is little context to disambiguate between e.g. monitor and OSD clients
because almost everything is inlined.  gdb sneakily stops at the first
matching symbol, so one has to resort to nm and addr2line.

Some of these are already prefixed with mon_, osd_ or mds_.  Let's do
the same for all others.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Acked-by: Jeff Layton <jlayton@kernel.org>