drm/amd/display: Fix a test CalculatePrefetchSchedule()

It is likely Height was expected here, instead of Width.

Test the correct variable.

Fixes: 17529ea2 ("drm/amd/display: Optimizations for DML math")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dml/dcn21/display_mode_vba_21.c

@@ -810,7 +810,7 @@ static bool CalculatePrefetchSchedule(
 			*swath_width_chroma_ub = dml_ceil(SwathWidthY / 2 - 1, myPipe->BlockWidth256BytesC) + myPipe->BlockWidth256BytesC;
 	} else {
 		*swath_width_luma_ub = dml_ceil(SwathWidthY - 1, myPipe->BlockHeight256BytesY) + myPipe->BlockHeight256BytesY;
-		if (myPipe->BlockWidth256BytesC > 0)
+		if (myPipe->BlockHeight256BytesC > 0)
 			*swath_width_chroma_ub = dml_ceil(SwathWidthY / 2 - 1, myPipe->BlockHeight256BytesC) + myPipe->BlockHeight256BytesC;
 	}