soc/fsl/qe: fix gpio save_regs functions

of_mm_gpiochip_add_data() calls mm_gc->save_regs() before
setting the data. Therefore ->save_regs() cannot use
gpiochip_get_data()

An Oops is encountered without this fix.

fixes: 1e714e54 ("powerpc: qe_lib-gpio: use gpiochip data pointer")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: <stable@vger.kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Scott Wood <oss@buserror.net>

drivers/soc/fsl/qe/gpio.c

@@ -41,7 +41,8 @@ struct qe_gpio_chip {
 
 static void qe_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
 {
-	struct qe_gpio_chip *qe_gc = gpiochip_get_data(&mm_gc->gc);
+	struct qe_gpio_chip *qe_gc =
+		container_of(mm_gc, struct qe_gpio_chip, mm_gc);
 	struct qe_pio_regs __iomem *regs = mm_gc->regs;
 
 	qe_gc->cpdata = in_be32(&regs->cpdata);