Revert "Small fix: Use const value on IsHashreeDisabled"

This reverts commit f5d8773169bbe355597d2a584560963670c99c70.

Reason for revert: Identified as culprit for broken tests: b/317470107

Change-Id: If599c688bb4bbe800270881451fa5ac1f6898aff
diff --git a/init/first_stage_mount.cpp b/init/first_stage_mount.cpp
index c0b9281..b5292a4 100644
--- a/init/first_stage_mount.cpp
+++ b/init/first_stage_mount.cpp
@@ -732,7 +732,7 @@
     return true;
 }
 
-bool IsHashtreeDisabled(const AvbHandle& vbmeta, const std::string& mount_point) {
+bool IsHashtreeDisabled(const AvbHandle& vbmeta, std::string mount_point) {
     if (vbmeta.status() == AvbHandleStatus::kHashtreeDisabled ||
         vbmeta.status() == AvbHandleStatus::kVerificationDisabled) {
         LOG(ERROR) << "Top-level vbmeta is disabled, skip Hashtree setup for " << mount_point;