cifs: add addr= mount option alias for ip=

When you look in /proc/mounts, the address of the server gets displayed
as "addr=". That's really a better option to use anyway since it's more
generic. What if we eventually want to support non-IP transports? It
also makes CIFS option consistent with the NFS option of the same name.

Begin the migration to that option name by adding an alias for ip=
called addr=.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>