mmc: sdhci: check voltage range only on regulators aware of voltage value

Some regulators don't report any voltage values, so checking supported
voltage range results in disabling all SDHCI_CAN_VDD_* flags and
registration failure. This patch finally provides a correct fix for the
registration of SDHCI driver with all possible voltage regulators:
dummy, fixed and regulated without using regulator_count_voltages()
hacks.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci.c

@@ -2976,7 +2976,11 @@ int sdhci_add_host(struct sdhci_host *host)
 	}
 
 #ifdef CONFIG_REGULATOR
-	if (host->vmmc) {
+	/*
+	 * Voltage range check makes sense only if regulator reports
+	 * any voltage value.
+	 */
+	if (host->vmmc && regulator_get_voltage(host->vmmc) > 0) {
 		ret = regulator_is_supported_voltage(host->vmmc, 2700000,
 			3600000);
 		if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_330)))