staging:board: remove unnecessary function

Remove the unnecessary 'of_can_translate_address',
which is already removed in commit
d9c6866be8a145e32da616d8dcbae806032d75b5 ("of: kill off
of_can_translate_address").

Signed-off-by: Tsung-Han Lin <tsunghan.tw@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>