mount.cifs: reinstate ip= as an override for address resolution

mount.cifs: reinstate ip= as an override for address resolution

The manpage says:

       ip=arg
           sets the destination IP address. This option is set automatically
           if the server name portion of the requested UNC name can be
           resolved so rarely needs to be specified by the user.

...but recent changes have made it not work anymore as an override if
someone specifies an ip= option as part of the mount options. Reinstate
that behavior by copying the ip= option verbatim into the addrlist of
the parsed options struct and then skipping the name resolution. That
should allow the ip= option to pass unadulterated to the kernel.

Signed-off-by: Jeff Layton <jlayton@samba.org>