omx: validate only standard OMX roles

Test uses ::android::GetComponentRole to get OMX role for media type
that only supports standard types (on GSI where VTS is run).

Bug: 164550113
Bug: 171536493
Bug: 194827876
Test: atest VtsHalMediaOmxV1_0TargetStoreTest

Change-Id: Ia9e64c8d887518f6c7d8c650a942bad7ce3457f0
(cherry picked from commit 9bb689da)