Remove unnecessary array_reverse() from wp_get_post_revisions().

WP_Query properly handles multiple 'orderby' values since [28541].

fixes #26042.
Built from https://develop.svn.wordpress.org/trunk@28543


git-svn-id: http://core.svn.wordpress.org/trunk@28369 1a063a9b-81f0-0310-95a4-ce76da25c4cd