drm/i915: Set rawclk earlier during mmio probe

Older platforms use rawclk to derive the CS clock. rawclk is being
determined during intel_device_info_init(), and so that needs to be
pushed slightly earlier.

Fixes: f170523a ("drm/i915/gt: Consolidate the CS timestamp clocks")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210104115145.24460-2-chris@chris-wilson.co.uk