Steps:
Go to the webstore https://store.sonyentertainmentnetwork.com/
Search for the PS3 version, and "buy" the demo.
Then search for the Vita version and "buy" its demo too.
Go back to the PS3 version and add the complete version to the cart. It should show up as free when you go to the cart and once you redeem that one you automatically get the Vita version as well.
Edit: EU store only it seems.(although for PS3 users: You can easily create a EU account in 5 minutes and do this. After downloading it you can use your US account with it. )Also it seems that the PS4 edition is not the actual thing, just a trial. Sorry there.
EDIT 2: It's fixed.
Go to the webstore https://store.sonyentertainmentnetwork.com/
Search for the PS3 version, and "buy" the demo.
Then search for the Vita version and "buy" its demo too.
Go back to the PS3 version and add the complete version to the cart. It should show up as free when you go to the cart and once you redeem that one you automatically get the Vita version as well.
Edit: EU store only it seems.(although for PS3 users: You can easily create a EU account in 5 minutes and do this. After downloading it you can use your US account with it. )Also it seems that the PS4 edition is not the actual thing, just a trial. Sorry there.
EDIT 2: It's fixed.