Cleanup ImageInterface.SetImageVariation

This change modifies the interface method of
ImageInterface.SetImageVariation so that the image variation is set
directly at the caller image variation module, instead of passing the
pointer to set the image variation.

Test: m nothing
Change-Id: Ice92b2496dbe9e342edf5542946620ae409f7d4f
diff --git a/build/soong/selinux_contexts.go b/build/soong/selinux_contexts.go
index d0bbc28..a65de35 100644
--- a/build/soong/selinux_contexts.go
+++ b/build/soong/selinux_contexts.go
@@ -255,7 +255,7 @@
 	return nil
 }
 
-func (m *selinuxContextsModule) SetImageVariation(ctx android.BaseModuleContext, variation string, module android.Module) {
+func (m *selinuxContextsModule) SetImageVariation(ctx android.BaseModuleContext, variation string) {
 }
 
 var _ android.ImageInterface = (*selinuxContextsModule)(nil)
@@ -730,7 +730,7 @@
 	return nil
 }
 
-func (m *contextsTestModule) SetImageVariation(ctx android.BaseModuleContext, variation string, module android.Module) {
+func (m *contextsTestModule) SetImageVariation(ctx android.BaseModuleContext, variation string) {
 }
 
 var _ android.ImageInterface = (*contextsTestModule)(nil)