mtd/maps/physmap: catch failure to register MTD_PHYSMAP_COMPAT device

If the default Kconfig values are used with MTD_PHYSMAP_COMPAT you end
up with a resource where end < start.  This causes __request_resource to
return a conflict which then returns an -EBUSY error code.  The current
physmap.c code just assumes that the platfom_device_register will always
succeed.

Catch this failure during the physmap_init and propogate the error.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/maps/physmap.c

@@ -264,8 +264,11 @@ static int __init physmap_init(void)
 
 	err = platform_driver_register(&physmap_flash_driver);
 #ifdef CONFIG_MTD_PHYSMAP_COMPAT
-	if (err == 0)
-		platform_device_register(&physmap_flash);
+	if (err == 0) {
+		err = platform_device_register(&physmap_flash);
+		if (err)
+			platform_driver_unregister(&physmap_flash_driver);
+	}
 #endif
 
 	return err;