drm/i915: Pass intel_crtc to ironlake_fdi_disable()

Switch to intel_crtc from drm_crtc.

Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191118164430.27265-6-ville.syrjala@linux.intel.com