staging: comedi: adv_pci1723: cleanup "find pci device" code

Use for_each_pci_dev() instead of open-coding the loop using
pci_get_device().

Drop the printk error messages. They just add noise.

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>