staging: comedi: adv_pci1723: move comedi_pci_enable() into the attach

Use pci_is_enabled() in the "find pci device" function to determine if
the found pci device is not in use and move the comedi_pci_enable() call
into the attach.

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