Documentation: numaperf: eliminate duplicated word

Drop the duplicated word "not".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: linux-mm@vger.kernel.org
Cc: Mike Rapoport <rppt@kernel.org>
Link: https://lore.kernel.org/r/20200707180414.10467-2-rdunlap@infradead.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>