drm/i915: Check tgl+ SAGV watermarks properly

We know which WM0 (normal vs. SAGV) we supposedly programmed
into the hardware, so just check against that instead of accepting
either watermark as valid.

Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210226153204.1270-7-ville.syrjala@linux.intel.com
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 9d9ba63..854ffec 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4745,7 +4745,7 @@ icl_get_total_relative_data_rate(struct intel_atomic_state *state,
 	return total_data_rate;
 }
 
-static const struct skl_wm_level *
+const struct skl_wm_level *
 skl_plane_wm_level(const struct skl_pipe_wm *pipe_wm,
 		   enum plane_id plane_id,
 		   int level)
@@ -4758,7 +4758,7 @@ skl_plane_wm_level(const struct skl_pipe_wm *pipe_wm,
 	return &wm->wm[level];
 }
 
-static const struct skl_wm_level *
+const struct skl_wm_level *
 skl_plane_trans_wm(const struct skl_pipe_wm *pipe_wm,
 		   enum plane_id plane_id)
 {