linux-phytec-fsl

drm/i915: don't touch the PF regs if the power well is down

This solves some "unclaimed register" messages when booting the
machine with eDP attached.

V2: Rebase and add the comment requested by Daniel.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>