arch: imx: fix incorrect shutdown call for inactive video devices

Somehow I missed that ipuv3_fb_shutdown() can be called for inactive
devices, resulting in invalid memory access and preventing the kernel
from booting.

Fixes: 32da6773f62 ("video: imx: ipuv3: refactor to use dm-managed state")
Signed-off-by: Brian Ruley <brian.ruley@gehealthcare.com>
Reviewed-by: David Zang <davidzangcs@gmail.com>

arch/arm/mach-imx/cpu.c

@@ -310,7 +310,8 @@ void arch_preboot_os(void)
 	/* disable video before launching O/S */
 	rc = uclass_find_first_device(UCLASS_VIDEO, &dev);
 	while (!rc && dev) {
-		ipuv3_fb_shutdown(dev);
+		if (device_active(dev))
+			ipuv3_fb_shutdown(dev);
 		uclass_find_next_device(&dev);
 	}
 #endif