staging: comedi: hwdrv_apci1500: introduce z8536_reset()

staging: comedi: hwdrv_apci1500: introduce z8536_reset()

Introduce a helper function to reset the Z8536 CIO device.

Spinlock the initial reset of the Z8536 chip that puts it in State 0.
The z8536_{read,write} operations already do the spinlock to protect
the indirect register access.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>