ARM: pxa: Remove unused variables

The conf and of_id variables are assigned but never used, so they may as
well just be removed.

Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>