drm/i915: Pass pipe_config to fdi_link_train() functions

It is preferred to pass pipe_config to functions instead of accessing
crtc->config directly. Follow suit and pass pipe_config to the fdi link
train functions.

v2: Add const; s/pipe_config/crtc_state/ (Ville)
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/20170302125857.14665-5-ander.conselvan.de.oliveira@intel.com