drm/nv50: cast IGP memory location to u64 before shifting

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_mem.c

@@ -540,7 +540,8 @@ nouveau_mem_detect(struct drm_device *dev)
 		dev_priv->vram_size  = nv_rd32(dev, NV04_FIFO_DATA);
 		dev_priv->vram_size &= NV10_FIFO_DATA_RAM_AMOUNT_MB_MASK;
 		if (dev_priv->chipset == 0xaa || dev_priv->chipset == 0xac)
-			dev_priv->vram_sys_base = nv_rd32(dev, 0x100e10) << 12;
+			dev_priv->vram_sys_base = nv_rd32(dev, 0x100e10);
+			dev_priv->vram_sys_base <<= 12;
 	}
 
 	NV_INFO(dev, "Detected %dMiB VRAM\n", (int)(dev_priv->vram_size >> 20));