spi: pl022: don't use uninitialized variable

The num-cs property is a required property according to the binding
documentation.  However, if it is not present, the driver currently
simply uses random junk from the stack for the num-cs since the variable
whose pointer is passed to of_property_read_u32() is not initialized.
Signed-off-by: NRabin Vincent <rabinv@axis.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-pl022.c

@@ -2074,7 +2074,7 @@ pl022_platform_data_dt_get(struct device *dev)
 {
 	struct device_node *np = dev->of_node;
 	struct pl022_ssp_controller *pd;
-	u32 tmp;
+	u32 tmp = 0;
 
 	if (!np) {
 		dev_err(dev, "no dt node defined\n");