mmc: core: shut up "voltage-ranges unspecified" pr_info()

Each time a driver such as sdhci-esdhc-imx is probed, we get a info
printk complaining that the DT voltage-ranges property has not been
specified.

However, the DT binding specifically says that the voltage-ranges
property is optional.  That means we should not be complaining that
DT hasn't specified this property: by indicating that it's optional,
it is valid not to have the property in DT.

Silence the warning if the property is missing.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/core.c

@@ -1214,8 +1214,12 @@ int mmc_of_parse_voltage(struct device_node *np, u32 *mask)
 
 	voltage_ranges = of_get_property(np, "voltage-ranges", &num_ranges);
 	num_ranges = num_ranges / sizeof(*voltage_ranges) / 2;
-	if (!voltage_ranges || !num_ranges) {
-		pr_info("%s: voltage-ranges unspecified\n", np->full_name);
+	if (!voltage_ranges) {
+		pr_debug("%s: voltage-ranges unspecified\n", np->full_name);
+		return -EINVAL;
+	}
+	if (!num_ranges) {
+		pr_err("%s: voltage-ranges empty\n", np->full_name);
 		return -EINVAL;
 	}