Documentation: s390/vfio-ap: eliminate duplicated word

Drop the doubled word "the".

Signed-off-by: Randy Dunlap <[e-mail]>
Reviewed-by: Pierre Morel <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: [e-mail]
Cc: Tony Krowiak <[e-mail]>
Cc: Pierre Morel <[e-mail]>
Cc: Halil Pasic <[e-mail]>
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/s390/vfio-ap.rst

···
     assign_domain / unassign_domain:
       Write-only attributes for assigning/unassigning an AP usage domain to/from
       the mediated matrix device. To assign/unassign a domain, the domain
-      number of the the usage domain is echoed to the respective attribute
+      number of the usage domain is echoed to the respective attribute
       file.
     matrix:
       A read-only file for displaying the APQNs derived from the cross product