drm/i915: Move edram detection early_sanitize

In order to be able to have virtual functions for the MMIO, we need to
use the raw access function. To keep things simple, just move this to
our early_sanitize code in uncore.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>