libceph: generalize addr/ip parsing based on delimiter

... and remove hardcoded function name in ceph_parse_ips().

[ idryomov: delim parameter, drop CEPH_ADDR_PARSE_DEFAULT_DELIM ]

Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>