drm/i915: use the CPU and PCH transcoders on lpt_pch_enable

On Haswell/LPT, pipe, cpu_transcoder and pch_transcoder are different
things with different values, unlinke the previous gens. So here we
use the right thing at the right place.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
[danvet: apply the patch by hand due to the reorder patch sequence. We
also can't kill all uses of pipe where we should, since the fdi link
train code isn't fixed up yet on this baselin.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>