navit: upgrade to latest SRCREV and remove navit-icons

* separate directory cannot be fetched with subversion-1.7.0
  svn: E155000: '/OE/downloads/svn/navit.svn.sourceforge.net/svnroot/navit/trunk/navit/navit/xpm' is already a working copy for a different URL
  and other users had problem with navit-icons trying to downgrade to older SRCREV and then upgrading again when building navit (failing with unversioned directories)

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>