staging: comedi: amplc_pci230: add `pci230_` prefix to functions

Most functions in "amplc_pci230" are named with the prefix `pci230_`,
apart from one or two that have the prefix `amplc_pci230_` and a few
odd-balls with no particular prefix.  Rename the ones without a prefix
for consistency.

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