Input: serport - add compat handling for SPIOCSTYPE ioctl

commit a80d8b02751060a178bb1f7a6b7a93645a7a308b upstream.

When running a 32-bit inputattach utility in a 64-bit system, there will be
error code "inputattach: can't set device type". This is caused by the
serport device driver not supporting compat_ioctl, so that SPIOCSTYPE ioctl
fails.

Signed-off-by: John Sung <penmount.touch@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>