Having in mind the content is the same with the only difference being mobile friendly, your suggestion makes no sense. Why would you want to index your mobile content in the first place? SE will index your website content and you would want to redirect the mobile users to the mobile friendly version of it. Makes sense now? If you want good rankings, focus on content that is worth sharing, not page rank, not anything else. Besides, page rank is page rank, not website rank, so every page of your website has different page rank. it is good to have link to your home page from all your internal pages. Home page usually gets the most because you link to it the most.... etc, etc.