Remove unused variable mount_point

Since aosp/929692, this variable has been discard.

Test: manual

Signed-off-by: zhangyongpeng <zhangyongpeng@xiaomi.com>
Change-Id: I164766c9af06c0c19bc19b258cb866ed7cf36853
diff --git a/fs_mgr/libfs_avb/avb_util.cpp b/fs_mgr/libfs_avb/avb_util.cpp
index 85dbb36..90b65ce 100644
--- a/fs_mgr/libfs_avb/avb_util.cpp
+++ b/fs_mgr/libfs_avb/avb_util.cpp
@@ -101,7 +101,6 @@
     if (wait_for_verity_dev) timeout = 1s;
 
     std::string dev_path;
-    const std::string mount_point(Basename(fstab_entry->mount_point));
     const std::string device_name(GetVerityDeviceName(*fstab_entry));
     android::dm::DeviceMapper& dm = android::dm::DeviceMapper::Instance();
     if (!dm.CreateDevice(device_name, table, &dev_path, timeout)) {