Documentation/driver-api: driver-model/platform: drop doubled word

Drop the doubled word "that".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200704034502.17199-12-rdunlap@infradead.org


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