Based on the comments under this post the options for placing braces were changed. So this post is not relevant anymore and new information you can find here.
When you select PHP language in the formatting setting then in Category combo box you can select category Braces. The panel for this category contains only one combo box, where you can define the position of braces. There are three values - Same Line, New Line and Preserve Existing. The default value is Same Line. See the picture.
I'm not sure whether this one option is sufficient. Does someone have a requirement to offer more options for the braces? For example the Java formatting has options that allow to set different behavior for class declaration, methods declaration and other cases. Also it allows to set that braces are indented on the new line.