Change number of posts on first page of posts loop.

[Arihantkankariya09]

Reference:- https://secure.helpscout.net/conversation/1162083320/129238?folderId=3243584

Scenario by the user:- When he sets 12 as number of posts than on the first page the first post is size big which leads to a blank space at the last, from the next pages the posts are evenly distributed and there is no blank space.