Added read phone state permission for getNetworkCountryIso

The slot based version of getNetworkCountryIso is a system API.
So it needs to be gaurded by permission.

Bug: 141646066
Test: Telephony sanity tests
Merged-In: I810ff0b77b93870ae3f62769977c7094789d0a5a
Change-Id: I810ff0b77b93870ae3f62769977c7094789d0a5a
(cherry picked from commit 105f6506)