Revert "Update min_sdk_version from SdkSpec to ApiLevel"

Revert submission 2457063

Reason for revert: Broken udc-dev

Reverted changes: /q/submissionid:2457063

Change-Id: Id6349fc1318877044af713c914a0afd437d3d2d5
diff --git a/java/rro.go b/java/rro.go
index 49737b9..9d0667c 100644
--- a/java/rro.go
+++ b/java/rro.go
@@ -175,11 +175,11 @@
 	return ""
 }
 
-func (r *RuntimeResourceOverlay) MinSdkVersion(ctx android.EarlyModuleContext) android.ApiLevel {
+func (r *RuntimeResourceOverlay) MinSdkVersion(ctx android.EarlyModuleContext) android.SdkSpec {
 	if r.properties.Min_sdk_version != nil {
-		return android.ApiLevelFrom(ctx, *r.properties.Min_sdk_version)
+		return android.SdkSpecFrom(ctx, *r.properties.Min_sdk_version)
 	}
-	return r.SdkVersion(ctx).ApiLevel
+	return r.SdkVersion(ctx)
 }
 
 func (r *RuntimeResourceOverlay) ReplaceMaxSdkVersionPlaceholder(ctx android.EarlyModuleContext) android.SdkSpec {