Saved reports view: fix missing icon error

PR #841 removed view_textual.png from sources, although this
icon was still being referenced from saved reports view, causing
the following error:

Started GET "/images/toolbars/view_textual.png"
No route matches [GET] "/images/toolbars/view_textual.png"
...

view_list.png is identical to view_textual.png, so let's
use that icon instead.