staging: comedi: amplc_pci224: __devinit pci224_attach_pci()

pci224_attach_pci() is only called during PCI probe, indirectly via
comedi_pci_auto_config(), so it can be marked __devinit.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>