drm/i915: Pass intel_crtc to intel_lpt_pch_enable()

The function intel_lpt_pch_enable() needs an intel_crtc so pass that
instead of the generic crtc type.

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170302125857.14665-3-ander.conselvan.de.oliveira@intel.com