Rename device_config --> aconfig and definitions --> declarations

Bug: 285303012
Test: for x in next trunk trunk_food trunk_staging ; do lunch aosp_panther-$x-eng ; m nothing ; done
Change-Id: I3375f46b3ecbbc516d1bee6ab3f80725fcccde8f
diff --git a/android/variable.go b/android/variable.go
index c5f1823..00315bc 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -477,8 +477,8 @@
 	ProductBrand        string   `json:",omitempty"`
 	BuildVersionTags    []string `json:",omitempty"`
 
-	ReleaseVersion               string   `json:",omitempty"`
-	ReleaseDeviceConfigValueSets []string `json:",omitempty"`
+	ReleaseVersion          string   `json:",omitempty"`
+	ReleaseAconfigValueSets []string `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {