docs: no structured comments in fs/file_table.c

Remove the kernel-doc directive, since there are only warnings to be found
there.
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/filesystems/api-summary.rst

@@ -89,9 +89,6 @@ Other Functions
 .. kernel-doc:: fs/direct-io.c
    :export:
 
-.. kernel-doc:: fs/file_table.c
-   :export:
-
 .. kernel-doc:: fs/libfs.c
    :export: