drm/i915: add haswell_set_pipeconf

It's a copy of ironlake_set_pipeconf with 2 differences:
  - There is no BPC field to set.
  - The interlaced mask is now 2 bits instead of 3.

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>