soc/tegra: cbb: tegra194: Use of_address_count() helper

After commit 16988c74 ("of/address: introduce of_address_count() helper"),
We can use of_address_count() to instead of open-coding it.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>