swap: Remove obsolete sentence

Currently there are no ->swap_{in,out} method in address_space_operations
sructure definition, so the statement that anything is going to be proxied
through them is wrong.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/filesystems/vfs.txt

@@ -829,9 +829,7 @@ struct address_space_operations {
   swap_activate: Called when swapon is used on a file to allocate
 	space if necessary and pin the block lookup information in
 	memory. A return value of zero indicates success,
-	in which case this file can be used to back swapspace. The
-	swapspace operations will be proxied to this address space's
-	->swap_{out,in} methods.
+	in which case this file can be used to back swapspace.
 
   swap_deactivate: Called during swapoff on files where swap_activate
 	was successful.