drm/i915: use TU_SIZE macro at intel_dp_set_m_n

Much simpler and looks more like the M/N code inside intel_display.c.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -794,9 +794,7 @@ intel_dp_set_m_n(struct drm_crtc *crtc, struct drm_display_mode *mode,
 			     mode->clock, adjusted_mode->clock, &m_n);
 
 	if (HAS_PCH_SPLIT(dev)) {
-		I915_WRITE(TRANSDATA_M1(pipe),
-			   ((m_n.tu - 1) << PIPE_GMCH_DATA_M_TU_SIZE_SHIFT) |
-			   m_n.gmch_m);
+		I915_WRITE(TRANSDATA_M1(pipe), TU_SIZE(m_n.tu) | m_n.gmch_m);
 		I915_WRITE(TRANSDATA_N1(pipe), m_n.gmch_n);
 		I915_WRITE(TRANSDPLINK_M1(pipe), m_n.link_m);
 		I915_WRITE(TRANSDPLINK_N1(pipe), m_n.link_n);
@@ -807,8 +805,7 @@ intel_dp_set_m_n(struct drm_crtc *crtc, struct drm_display_mode *mode,
 		I915_WRITE(PIPE_LINK_N1(pipe), m_n.link_n);
 	} else {
 		I915_WRITE(PIPE_GMCH_DATA_M(pipe),
-			   ((m_n.tu - 1) << PIPE_GMCH_DATA_M_TU_SIZE_SHIFT) |
-			   m_n.gmch_m);
+			   TU_SIZE(m_n.tu) | m_n.gmch_m);
 		I915_WRITE(PIPE_GMCH_DATA_N(pipe), m_n.gmch_n);
 		I915_WRITE(PIPE_DP_LINK_M(pipe), m_n.link_m);
 		I915_WRITE(PIPE_DP_LINK_N(pipe), m_n.link_n);