Add GNSS HAL 2.1

Bug: 136136192
Bug: 141758837

Test: atest VtsHalGnssV2_1TargetTest
Change-Id: I8e6d52695c8ab0aeacacb0107a6c0c8271983ed3
diff --git a/gnss/2.1/default/OWNERS b/gnss/2.1/default/OWNERS
new file mode 100644
index 0000000..b7b4a2e
--- /dev/null
+++ b/gnss/2.1/default/OWNERS
@@ -0,0 +1,4 @@
+gomo@google.com
+smalkos@google.com
+wyattriley@google.com
+yuhany@google.com