NEW YORK (Reuters) – Activist billionaire investor Carl Icahn said Tuesday on CNBC that his firm has $2 billion invested in shares of technology giant Apple Inc.. Shares of Apple rose over 2 percent on Tuesday on news that Icahn had dinner with Apple chief executive Tim Cook on Monday and “pushed hard” for a buyback. “Had a cordial dinner with Tim last night. We pushed hard for a 150 billion buyback. We decided to continue dialogue in about three weeks,” Icahn tweeted on Tuesday. …