ovl: pass name buffer to ovl_start_creating_temp()

ovl: pass name buffer to ovl_start_creating_temp()

Now ovl_start_creating_temp() is passed a buffer in which to store the
temp name.  This will be useful in a future patch were ovl_create_real()
will need access to that name.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20260224222542.3458677-12-neilb@ownmail.net
Signed-off-by: Christian Brauner <brauner@kernel.org>