staging: comedi: amplc_pci230: Remove forward declarations 2

Remove some forward function declarations: pci230_ct_setup_ns_mode(),
pci230_ns_to_single_timer(), pci230_cancel_ct().  Also need to move:
divide_ns().

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