Remove <p> tag from edd_checkout_submit() that is causing 2 empty <p> tags in markup

- Causes 2 empty `<p>` tag's in markup, one at top and one at bottom, resulting in unnecessary space in themes when the `<p>` has margin bottom or line height applied to it.
- The submit button appears inside `<p>` tag in the code, but outside in html markup

Can't see any other reason to keep it there. When firing any functions on the hook, a developer could add their own wrapper if necessary.

![Screen Shot 2013-03-07 at 12 50 00 PM](https://f.cloud.github.com/assets/52581/230233/94bdb200-86b8-11e2-9194-1b2c188bdbf7.png)