fix below warning reported by includecheck
./drivers/staging/speakup/serialio.h: linux/serial.h is included more
than once.
Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>