drm/i915: split up fdi_set_m_n into computation and hw setup

And also move the computed m_n values into the pipe_config. This is a
prep step to move the fdi state computation completely into the
prepare phase of the modeset sequence. Which will allow us to handle
fdi link bw constraints in a better way.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index cc075a3..48f309e 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -250,8 +250,9 @@
 		u32 size;
 	} pch_pfit;
 
-	/* FDI lanes used, only valid if has_pch_encoder is set. */
+	/* FDI configuration, only valid if has_pch_encoder is set. */
 	int fdi_lanes;
+	struct intel_link_m_n fdi_m_n;
 };
 
 struct intel_crtc {