Document & Media Display portlet does not reflect the "documents per page" on change of configuration.

Reproduced in 6.1.x & Trunk rev. 116419

Steps to reproduce:
1) Login with test@liferay.com
2) Upload 30 documents to Documents and Media
3) Go back to liferay.com and add a "Files" page
4) Add Documents and Media Display portlet on the page
5) You will see 20 files in a page, with pagination links.
6) Click on next page link and go to the 2nd page.
7) Now open configuration pop-up and in "Document Listing" change the Docuements per page = 30.
8) Click on save, the portlet is reloaded through ajax but it still shows "Showing 21 - 30 of 30 results" with pagination links instead of "Showing 1-30 of 30 results" and no pagination links.
9) Try refreshing the page but still it shows the same thing.
10) Try click on next previous link and still it shows 20 results per page.
11) Now click on the "Files" page link and it shows the display correctly i.e. "Showing 1-30 of 30 results".