vfs: add initial support for CONFIG_DEBUG_VFS

Small collection of macros taken from mmdebug.h

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250209185523.745956-2-mjguzik@gmail.com


Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>