Make CreateVariations return []android.Module

Test: soong tests
Change-Id: I9bc40642c4902392eb8193bf73e32b7f1c18c14e
diff --git a/android/apex.go b/android/apex.go
index 5118a0a..44387cd 100644
--- a/android/apex.go
+++ b/android/apex.go
@@ -17,8 +17,6 @@
 import (
 	"sort"
 	"sync"
-
-	"github.com/google/blueprint"
 )
 
 // ApexModule is the interface that a module type is expected to implement if
@@ -69,7 +67,7 @@
 
 	// Mutate this module into one or more variants each of which is built
 	// for an APEX marked via BuildForApex().
-	CreateApexVariations(mctx BottomUpMutatorContext) []blueprint.Module
+	CreateApexVariations(mctx BottomUpMutatorContext) []Module
 
 	// Sets the name of the apex variant of this module. Called inside
 	// CreateApexVariations.
@@ -176,7 +174,7 @@
 	}
 }
 
-func (m *ApexModuleBase) CreateApexVariations(mctx BottomUpMutatorContext) []blueprint.Module {
+func (m *ApexModuleBase) CreateApexVariations(mctx BottomUpMutatorContext) []Module {
 	if len(m.apexVariations) > 0 {
 		m.checkApexAvailableProperty(mctx)
 		sort.Strings(m.apexVariations)