gpio: dwapb: fix NULL pointer dereference at dwapb_gpio_suspend()

Following Calltrace is found when running echo freeze > /sys/power/state.

[  272.755506] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
[  272.755585] Call trace:
[  272.755587]  dwapb_gpio_suspend+0x18/0x318
[  272.755588]  pm_generic_suspend+0x2c/0x48
[  272.755595]  acpi_subsys_suspend+0x60/0x70
[  272.755599]  dpm_run_callback.isra.18+0x40/0xe0
[  272.755601]  __device_suspend+0xf4/0x360

The reason is platform_set_drvdata() is deleted, and dwapb_gpio_suspend()
get *gpio by dev_get_drvdata().

Fixes: feeaefd ("gpio: dwapb: Use resource managed GPIO-chip add data method")
Signed-off-by: Luo Jiaxing <luojiaxing@huawei.com>
Acked-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

drivers/gpio/gpio-dwapb.c

@@ -724,6 +724,8 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
 			return err;
 	}
 
+	platform_set_drvdata(pdev, gpio);
+
 	return 0;
 }