Zelda does not have the triforce in this game as it has not split yet though.
Then what exactly is the "holiness" within Zelda?
The "Goddess" was intrusted with a power by the "Gods of Old" and this was likley the Triforce.
I'm not saying that she does have it for the simple reason that Ocarina of Time clearly states that it is in the Sacred Realm, but I am also open to it having been moved from that location to protect it.
How do we know that the Triforce was not moved from the Sacred Realm to protect it from the Demon Tribe and intrusted to the "Goddess"?
I believe that perhaps it was moved from the Sacred Realm and intrusted to the "Goddess" to protect it from the Demon Tribe and that she passed it on to her descendents.
This could explain why Zelda would have it.
However I also believe that perhaps Zelda does not posses the Triforce itself but rather is a key to it or where it is.
Either way would explain why Ghirahim is after Zelda.
Makes some sense if you think about it I think.