Add BoardKernelModuleInterfaceVersions.

This is a list of KMI versions for this board. Only gki_apex modules
with matching kmi_version field is enabled.

Test: build GKI apexes
Bug: 162888350
Change-Id: Ieb2116b79e3985ba15155a3cb8a2c340b46473c7
diff --git a/android/variable.go b/android/variable.go
index c1e1b42..8799d58 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -345,7 +345,8 @@
 
 	BoardUsesRecoveryAsBoot *bool `json:",omitempty"`
 
-	BoardKernelBinaries []string `json:",omitempty"`
+	BoardKernelBinaries                []string `json:",omitempty"`
+	BoardKernelModuleInterfaceVersions []string `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {