kern/mips/arc/init: Add missing grub_strdup() failure check

If grub_strdup() fails, it returns NULL and passing NULL further down to
the code can lead to segmentation fault or an undefined behavior.

Signed-off-by: Avnish Chouhan <avnish@linux.ibm.com>
Reviewed-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/kern/mips/arc/init.c

@@ -403,6 +403,9 @@ grub_machine_get_bootlocation (char **device, char **path)
       if (!syspart)
 	return;
       loaddev = grub_strdup (syspart);
+      if (loaddev == NULL)
+        return;
+
     }
 
   partptr = get_part (loaddev);