Fix Gran Turismo's text

Credit goes to Unknown for the fix. Fixes https://github.com/hrydgard/ppsspp/issues/2906, and as far as I know, doesn't affect other games, though I tested a small sample(8 games or so).

According to unknown, the game was using the same texture address to render, even though it's being overwritten in DoBlockTransfer. The texture cache code was never even being called.