Add the "virtual" instance for face HAL retroactively

Test: m
Bug: 300320120
Change-Id: I395865e9af3679d8cb6cd888dfc3438fa3389f95
diff --git a/compatibility_matrices/compatibility_matrix.8.xml b/compatibility_matrices/compatibility_matrix.8.xml
index 098270f..0f82e5f 100644
--- a/compatibility_matrices/compatibility_matrix.8.xml
+++ b/compatibility_matrices/compatibility_matrix.8.xml
@@ -133,6 +133,7 @@
         <interface>
             <name>IFace</name>
             <instance>default</instance>
+            <instance>virtual</instance>
         </interface>
     </hal>
     <hal format="aidl" optional="true">