[x86] drm/i915: update rawclk also on resume

A problem was found on the Lenovo P1Gen2 whereby it would sometimes blackscreen on suspend and resume. The issue occurs because there are two clocks available and on resume the i915 driver uses the wrong clock and therefore doesn't allow enough time for the panel to complete it's initialisation This is a backport of the patch Intel submitted upstream (5.4-rc8) to resolve the issue. It has been tested on the P1Gen2 and solves the issue. I believe it will also solve similar problems on other platforms using Intel CPUs that have multiple clock inputs

Note - this is only my second attempt at backporting a patch and I made some mistakes in my first attempt which a few people have been kind enough to educate me on. Please do let me if there is anything incorrect or that I should be doing differently with this one - it's a simpler patch so I'm hoping goes more smoothly.