drm/nv50: hopefully handle the DDR2/DDR3 memtype detection somewhat better

M version 2 appears to have a table with some form of memory type info
available.

NVIDIA appear to ignore the table information except for this DDR2/DDR3
case (which has the same value in 0x100714).  My guess is this is due to
some of the supported memory types not being represented in the table.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nv50_vram.c b/drivers/gpu/drm/nouveau/nv50_vram.c
index 8406966..1467efc 100644
--- a/drivers/gpu/drm/nouveau/nv50_vram.c
+++ b/drivers/gpu/drm/nouveau/nv50_vram.c
@@ -195,10 +195,10 @@
 	switch (pfb714 & 0x00000007) {
 	case 0: dev_priv->vram_type = NV_MEM_TYPE_DDR1; break;
 	case 1:
-		if (0 /* some currently unknown condition */)
-			dev_priv->vram_type = NV_MEM_TYPE_DDR2;
-		else
+		if (nouveau_mem_vbios_type(dev) == NV_MEM_TYPE_DDR3)
 			dev_priv->vram_type = NV_MEM_TYPE_DDR3;
+		else
+			dev_priv->vram_type = NV_MEM_TYPE_DDR2;
 		break;
 	case 2: dev_priv->vram_type = NV_MEM_TYPE_GDDR3; break;
 	case 3: dev_priv->vram_type = NV_MEM_TYPE_GDDR4; break;