Remove redundant memory usage in ERC2981 royaltyInfo (#4538)

Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>

contracts/token/common/ERC2981.sol

@@ -59,15 +59,18 @@ abstract contract ERC2981 is IERC2981, ERC165 {
      * @inheritdoc IERC2981
      */
     function royaltyInfo(uint256 tokenId, uint256 salePrice) public view virtual returns (address, uint256) {
-        RoyaltyInfo memory royalty = _tokenRoyaltyInfo[tokenId];
+        RoyaltyInfo storage _royaltyInfo = _tokenRoyaltyInfo[tokenId];
+        address royaltyReceiver = _royaltyInfo.receiver;
+        uint96 royaltyFraction = _royaltyInfo.royaltyFraction;
 
-        if (royalty.receiver == address(0)) {
-            royalty = _defaultRoyaltyInfo;
+        if (royaltyReceiver == address(0)) {
+            royaltyReceiver = _defaultRoyaltyInfo.receiver;
+            royaltyFraction = _defaultRoyaltyInfo.royaltyFraction;
         }
 
-        uint256 royaltyAmount = (salePrice * royalty.royaltyFraction) / _feeDenominator();
+        uint256 royaltyAmount = (salePrice * royaltyFraction) / _feeDenominator();
 
-        return (royalty.receiver, royaltyAmount);
+        return (royaltyReceiver, royaltyAmount);
     }
 
     /**