Change icon for the 'Edit...' context menu entry in Places panel

Summary:
The current icon is used for displaying the Properties context menu
in other places in dolphin. Change to edit-entry.

Test Plan: Right-click on a place in the Places panel.

Reviewers: Dolphin, VDG, ngraham

Reviewed By: Dolphin, VDG, ngraham

Subscribers: broulik, kfm-devel

Tags: Dolphin

Differential Revision: https://phabricator.kde.org/D15938