Documentation/driver-api: xillybus: drop doubled word

Drop the doubled word "the".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Acked-by: Eli Billauer <eli.billauer@gmail.com>
Link: https://lore.kernel.org/r/20200704034502.17199-18-rdunlap@infradead.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>