mfd: vexpress: Make the driver optional for arm and arm64

The driver can be used on either arm or arm64 platforms, but
the latter doesn't have any platform-specific configuration
options, so it must be possible to manually enable the driver.

As the gpiolib is optional for arm64 arch, the gpio/led code
must be compiled conditionally.

Signed-off-by: Pawel Moll <[e-mail]>
Acked-by: Catalin Marinas <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

drivers/mfd/Kconfig

···
 endmenu
 
 config VEXPRESS_CONFIG
-	bool
+	bool "ARM Versatile Express platform infrastructure"
+	depends on ARM || ARM64
 	help
 	  Platform configuration infrastructure for the ARM Ltd.
 	  Versatile Express.

drivers/mfd/vexpress-sysreg.c

···
 }
 
 
+#ifdef CONFIG_GPIOLIB
+
 #define VEXPRESS_SYSREG_GPIO(_name, _reg, _value) \
 	[VEXPRESS_GPIO_##_name] = { \
 		.reg = _reg, \
···
 	.leds = vexpress_sysreg_leds,
 };
 
+#endif
+
 
 static ssize_t vexpress_sysreg_sys_id_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
···
 	setup_timer(&vexpress_sysreg_config_timer,
 			vexpress_sysreg_config_complete, 0);
 
+	vexpress_sysreg_dev = &pdev->dev;
+
+#ifdef CONFIG_GPIOLIB
 	vexpress_sysreg_gpio_chip.dev = &pdev->dev;
 	err = gpiochip_add(&vexpress_sysreg_gpio_chip);
 	if (err) {
···
 		return err;
 	}
 
-	vexpress_sysreg_dev = &pdev->dev;
-
 	platform_device_register_data(vexpress_sysreg_dev, "leds-gpio",
 			PLATFORM_DEVID_AUTO, &vexpress_sysreg_leds_pdata,
 			sizeof(vexpress_sysreg_leds_pdata));
+#endif
 
 	device_create_file(vexpress_sysreg_dev, &dev_attr_sys_id);