Set the NetworkInfo subtype to 0.

For non-telephony networks, this was always set to 0 before R.
In R, it is currently set to the same value as the network type.
This is incorrect because the two have different namespaces.
or example, currently, any network of type WIFI (==1) will have
a subtype of NETWORK_TYPE_GPRS (==1). Similarly, all ETHERNET
networks will have subtype NETWORK_TYPE_1XRTT, all VPN networks
will have a subtype of NETWORK_TYPE_TD_SCDMA, etd.

Bug: 161653721
Test: builds, boots
Change-Id: I07e111c1762e0021c931cefc27f193f78578748b