Blackfin SPI Driver: fix NULL pointer crash

Fix NULL pointer crash when cleaning up from invalid platform resources
Signed-off-by: NMike Frysinger <vapier.adi@gmail.com>
Signed-off-by: NBryan Wu <cooloney@kernel.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/spi/spi_bfin5xx.c

@@ -1178,6 +1178,9 @@ static void bfin_spi_cleanup(struct spi_device *spi)
 {
 	struct chip_data *chip = spi_get_ctldata(spi);
 
+	if (!chip)
+		return;
+
 	if ((chip->chip_select_num > 0)
 		&& (chip->chip_select_num <= spi->master->num_chipselect))
 		peripheral_free(ssel[spi->master->bus_num]