Use DAB_SID_EXT instead in DAB radio VTS

Checked if the same DAB_SID_EXT instead of DAB frequency exists as
the selector tuned to in DAB tune broadcast radio VTS.

Bug: 384062869
Flag: EXEMPT bugfix
Test: atest VtsHalBroadcastradioAidlTargetTest
Change-Id: Ifca54124af9304278aaca633457fd2461b6a8082