ovl: fix debug print in case of mkdir error

We want to print the name in case of mkdir failure and now we will
get a cryptic (efault) as name.

Fixes: c54b3869 ("VFS: Change vfs_mkdir() to return the dentry.")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/20250612072245.2825938-1-amir73il@gmail.com


Signed-off-by: Christian Brauner <brauner@kernel.org>