Imagination Technologies, UK-based designer of processor cores, has put itself up for sale, weeks after its investor and largest customer, Apple, said it would stop using Imagination’s GPU cores and create its own for future iDevices. This opened up the potential for a significant revenue hole – and possible future legal battles – for Imagination, which had already lost its long-time CEO, Sir Hossein Yossaie, as it struggled to diversify its product offerings. The company’s depressed shares leapt on the news that, as expected, it was seeking a buyer. It had already put its two non-GPU business units – MIPS, the venerable CPU core designer, and connectivity firm Ensigma – on the block and said there is interest in them.…