Documentation: eisa: Fix typo

Fix a typo in the description of the kernel parameter
eisa_bus.disable_dev within eisa.rst.

Signed-off-by: Albert Zhou <albert.zhou.50@gmail.com>
Link: https://lore.kernel.org/r/20221105080653.4741-1-albert.zhou.50@gmail.com


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