of: addr: Remove call to dev_count_cells() in of_get_address()

In of_get_address(), there is:

  dev_count_cells(dev, &na, &ns);

followed by:

  bus->count_cells(dev, &na, &ns);

but no codes in between use na/ns, hence the first call is useless.
By dropping the first call, dev_count_cells() is now useless too.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>