grubcfg: Don't error if /etc/default is missing.

It is created later in the function.

src/modules/grubcfg/main.py

@@ -29,9 +29,6 @@ def modify_grub_default(partitions, root_mount_point, distributor):
     use_splash = ""
     swap_uuid = ""
 
-    if not os.path.exists(default_dir):
-        return ("Directory does not exist", "The directory {} does not exist on "
-        "the target".format(default_dir))
     if os.path.exists(plymouth_bin):
         use_splash = "splash"