staging: comedi: adv_pci1710: remove 'ai_eos' from private data

This member of the private data is is not necessary. We can just check the
cmd->flags for TRIG_WAKE_EOS when needed. Remvoe the member.

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>