pxa2xx_spi: prevent panic case setup() fails

setup() may fail before ctldata is set, causing a kernel panic on
cleanup().

Signed-off-by: Daniel Ribeiro <[e-mail]>
Signed-off-by: David Brownell <[e-mail]>
Cc: Eric Miao <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/spi/pxa2xx_spi.c

···
 {
 	struct chip_data *chip = spi_get_ctldata(spi);
 
+	if (!chip)
+		return;
+
 	if (gpio_is_valid(chip->gpio_cs))
 		gpio_free(chip->gpio_cs);