drm/i915: remove pch_port argument form intel_enable_pipe

Now that we pass struct intel_crtc as an argument, there's no need for
it.

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