p54spi: fix potential null deref in p54spi.c

Fix a potential NULL dereference bug during
error handling in p54spi_probe.

This bug was discovered by smatch:
(http://repo.or.cz/w/smatch.git).
Signed-off-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NChristian Lamparter <chunkeey@web.de>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/p54/p54spi.c

@@ -635,7 +635,7 @@ static int __devinit p54spi_probe(struct spi_device *spi)
 
 	hw = p54_init_common(sizeof(*priv));
 	if (!hw) {
-		dev_err(&priv->spi->dev, "could not alloc ieee80211_hw");
+		dev_err(&spi->dev, "could not alloc ieee80211_hw");
 		return -ENOMEM;
 	}