Remove all references to QAccessible::Self

Remove all references to QAccessible::Self

navigate() to Self does not make any sense (its basically a clone).
It seems that its not that useful to return Self from relationTo(),
since it was only one place where relationTo() was called where it
checked for the Self flag. This was in the windows bridge, and we
could easily work around that.
If it really turns out that Self is useful, we can always add that
enum value back later.

Change-Id: I9ebb60da059a843de5e6fcab9e815b919afc6f2a
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@nokia.com>