drm/i915: Pass intel_crtc to fdi_link_train() hooks

The implementation of the fdi_link_train() hooks need an intel_crtc so
just 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/20170302125857.14665-2-ander.conselvan.de.oliveira@intel.com