According to Battlefield 4 users pre-order customers who received a code to download China Rising with their current-gen copy are not eligible to carry the content over when upgrading to a digital next-gen version.
EA user Buckethead232 encountered a problem when he paid to upgrade his PS3 version of Battlefield 4 to the PS4 version. He paid to upgrade his copy but he was unable to download the free map that was included with his original purchase. So naturally, he turned to EA for answers. What he learned was the new policy was that anyone who upgrades from a physical disc copy to their next gen counterpart has to pay $14.99 for the map or purchase premium.
Apparently the decision to no longer honor the free maps with their original purchase was decided midday on December 18. Two of his friends had also encountered the problem but were issued new map codes that same day.
Another EA user, the VanillaGorilla also came to EA with the same issue and was also told that he needs to purchase the map or Battlefield 4 premium.
So if you bought the current gen versions of Battlefield 4, unless you are willing to purchase the map content don't count on being able to grab the China Rising free. Players who purchased Battlefield 4 Premium on PS3 or Xbox 360 are able to transfer the content over to next-gen, however, including China Rising and all future DLC packs.