Staging: comedi: comedi_pci.h: remove comedi_pci_enable_no_regions

comedi_pci_enable_no_regions is not called by any comedi code
(in or out of the kernel tree), so remove it, so no one tries to
use it in the future.

Cc: David Schleef <ds@schleef.org>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>