drm/i915: Mark up a couple of KMS debug messages as such

For finding the panel fitter and PLL for a particular modeset is a part
of that modeset and should be included with the reset of the
DRM_DEBUG_KMS.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180913131629.3978-1-chris@chris-wilson.co.uk