fork: clean up ifdef logic around stack allocation

fork: clean up ifdef logic around stack allocation

There is an unneeded OR in the ifdef functions that are used to allocate
and free kernel stacks based on direct map or vmap.  Adding dynamic stack
support would complicate this logic even further.

Therefore, clean up by changing the order so OR is no longer needed.

Link: https://lkml.kernel.org/r/20250618-fork-fixes-v4-1-2e05a2e1f5fc@linaro.org
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/20240311164638.2015063-3-pasha.tatashin@soleen.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>