staging: comedi: amplc_pci230: rename pci230_ai_rinsn()

Rename the AI subdevice "insn_read" handler function `pci230_ai_rinsn()`
to `pci230_ai_insn_read()` 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>