spi_mpc8xxx: Fix uninitialized variable

This patch fixes the following warning:

CC      drivers/spi/spi_mpc8xxx.o
  spi_mpc8xxx.c: In function 'of_mpc8xxx_spi_probe':
  spi_mpc8xxx.c:681: warning: 'ret' may be used uninitialized in this function

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

drivers/spi/spi_mpc8xxx.c

@@ -709,6 +709,7 @@ static int of_mpc8xxx_spi_get_chipselects(struct device *dev)
 		gpio = of_get_gpio_flags(np, i, &flags);
 		if (!gpio_is_valid(gpio)) {
 			dev_err(dev, "invalid gpio #%d: %d\n", i, gpio);
+			ret = gpio;
 			goto err_loop;
 		}