staging: comedi: comedi_pci: introduce comedi_pci_detach()

Introduce a generic (*detach) function for comedi PCI drivers to handle
the boilerplate code needed to detach a PCI driver.

This function works similar to comedi_legacy_detach() where it will:

  * free the dev->irq if it has been requested
  * iounmap the dev->mmio addres if it has been ioremap'ed

The helper then calls comedi_pci_disable() to release the regions and
disable the PCI device.

Use the new helper directly for the (*detach) in the following cases:

  * where comedi_pci_disable() is used directly for the (*detach)
  * where the detach function is just boilerplate

Use the new helper in the (*detach) of the simpler PCI drivers. Call
the helper after disabling interrupts (reset) and before any additional
cleanup (kfree) to avoid any race conditions with the interrupt handler.

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>