Restore dumpsys iphonesubinfo

When Multi SIM was implemented, that broke dumpsys for several
telephony related services. The class that registers the service
does not override dump, though, but the info is available
in PhoneFactory and can be dumped via TelephonyDebugService.

Note: This change only fixes iphonesubinfo. Imms, isms and others are
still broken.

Change-Id: Ie5b8600c40b07c49c28b3df8a3c0d56527434710