SettingsProvider: fix data_enabled default lookup

We shouldn't set the MOBILE_DATA + phoneId keys because it will cause
collisions with other parts of the system that actually query
MOBILE_DATA + subId - leading to incorrect defaults.

TelephonyManager.getIntWithSubId() actually falls back to just
MOBILE_DATA for a specific sub id query, so we do not need to touch
these values, since it applies the same default to all sub ids anyways.

Ticket: CYNGNOS-3171

Change-Id: I38405000b3d641029080fb630eae4d128bd44719
Signed-off-by: Roman Birg <roman@cyngn.com>