staging: comedi: adv_pci1710: absorb move_block_from_fifo()

This function is only called by pci1710_handle_fifo(). Absorb it and clean up
pci1710_handle_fifo().

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