Well, it's not in the original Ocarina of Time so it's got to be new. There's a few Easter eggs in this game like if you roll into a certain crate in Gerudo Fortress you can see official artwork for Skyward Sword. So I bet it's kind of like that. I don't have a 3DS so I haven't seen the picture but I think it's just an easter egg.
I would think it would have to be something new. I've played Ocarina of Time for the N64 MANY MANY times and I'm never seen a poster in Kakariko Village, so yeah must be a little easter egg for the 3DS version.
When the game was put on to the 3DS many things were upgraded. Towns, Houses, and other things were all redone. Lot's of stuff was put into houses and other places because of the 3DS's higher graphic output. Within all of this there were many easter eggs to be found.