Remove appDirRoot argument from setupAppDir.

This is no longer needed, because vold can deduce this itself now.

Bug: 146419093
Test: builds
Change-Id: Ib4f4a4109919af683722a63b305b343ef5fe972d
diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index c141d2a..9eb7852 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -823,8 +823,7 @@
     return 0;
 }
 
-int VolumeManager::setupAppDir(const std::string& path, const std::string& appDirRoot,
-                               int32_t appUid) {
+int VolumeManager::setupAppDir(const std::string& path, int32_t appUid) {
     // Only offer to create directories for paths managed by vold
     if (!StartsWith(path, "/storage/")) {
         LOG(ERROR) << "Failed to find mounted volume for " << path;