memory: tegra30-emc: Fix panic on suspend

Trying to suspend driver results in a crash if timings aren't available in
device-tree.
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Fixes: e34212c7 ("memory: tegra: Introduce Tegra30 EMC driver")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/memory/tegra/tegra30-emc.c

@@ -1093,7 +1093,7 @@ static int tegra_emc_probe(struct platform_device *pdev)
 	if (of_get_child_count(pdev->dev.of_node) == 0) {
 		dev_info(&pdev->dev,
 			 "device-tree node doesn't have memory timings\n");
-		return 0;
+		return -ENODEV;
 	}
 
 	np = of_parse_phandle(pdev->dev.of_node, "nvidia,memory-controller", 0);