staging: gpib: Fix sending clear and trigger events

staging: gpib: Fix sending clear and trigger events

commit 92a2b74a6b5a5d9b076cd9aa75e63c6461cbd073 upstream.

This driver was not sending device clear or trigger events when the
board entered the DCAS or DTAS state respectively in device mode.

DCAS is the Device Clear Active State which is entered on receiving a
selective device clear message (SDC) or universal device clear message
(DCL) from the controller in charge.

DTAS is the Device Trigger Active State which is entered on receiving
a group execute trigger (GET) message from the controller.

In order for an application, implementing a particular device, to
detect when one of these states is entered the driver needs to send
the appropriate event.

Send the appropriate gpib_event when DCAS or DTAS is set in the
reported status word. This sets the DCAS or DTAS bits in the board's
status word which can be monitored by the application.

Fixes: 4e127de14fa7 ("staging: gpib: Add National Instruments USB GPIB driver")
Cc: stable <stable@kernel.org>
Tested-by: Dave Penkler <dpenkler@gmail.com>
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>