Add BARRING_TYPE_UNKNOWN to BarringInfoTest

Update BarringInfo behavior to account for UNKNOWN
barring type, which is used when the modem doesn't
report any barring info.

Bug: 143226991
Test: atest BarringInfoTest
Merged-In: Id675bdb52544a1604023d6b6b32324b148defc1f
Change-Id: Id675bdb52544a1604023d6b6b32324b148defc1f
(cherry picked from commit f4dd1542)