Documentation: spufs: correct a duplicate word typo

Fix a typo of "or" which should be "of".

Signed-off-by: Randy Dunlap <[e-mail]>
Cc: Jeremy Kerr <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: [e-mail]
Cc: Jonathan Corbet <[e-mail]>
Reviewed-by: Jeremy Kerr <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/filesystems/spufs/spufs.rst

···
               from the data buffer, updating the value of the specified signal
               notification register.  The signal  notification  register  will
               either be replaced with the input data or will be updated to the
-              bitwise OR or the old value and the input data, depending on the
+              bitwise OR of the old value and the input data, depending on the
               contents  of  the  signal1_type,  or  signal2_type respectively,
               file.