fork: use __vmalloc_node() for stack allocation

Replace __vmalloc_node_range() by __vmalloc_node().  The last variant
requires less parameters and it uses exactly the same arguments which are
partly now hidden inside __vmalloc_node().

This change does not change any functionality.  It makes the code a bit
simpler.

Link: https://lkml.kernel.org/r/20250317163614.166502-1-urezki@gmail.com


Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>