NFC: trf7970a: Remove support for 'vin-voltage-override' DT property

The 'vin-voltage-override' DT property is used by the trf7970a
driver to override the voltage presented to the driver by the
regulator subsystem.  This is unnecessary as properly specifying
the regulator chain via DT properties will accomplish the same
thing.  Therefore, remove support for 'vin-voltage-override'.

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/nfc/trf7970a.c

@@ -2005,12 +2005,6 @@ static int trf7970a_get_autosuspend_delay(struct device_node *np)
 	return autosuspend_delay;
 }
 
-static int trf7970a_get_vin_voltage_override(struct device_node *np,
-		u32 *vin_uvolts)
-{
-	return of_property_read_u32(np, "vin-voltage-override", vin_uvolts);
-}
-
 static int trf7970a_probe(struct spi_device *spi)
 {
 	struct device_node *np = spi->dev.of_node;
@@ -2108,10 +2102,7 @@ static int trf7970a_probe(struct spi_device *spi)
 		goto err_destroy_lock;
 	}
 
-	ret = trf7970a_get_vin_voltage_override(np, &uvolts);
-	if (ret)
-		uvolts = regulator_get_voltage(trf->regulator);
-
+	uvolts = regulator_get_voltage(trf->regulator);
 	if (uvolts > 4000000)
 		trf->chip_status_ctrl = TRF7970A_CHIP_STATUS_VRS5_3;