staging: comedi: ni_labpc_common: move calib readback value check/save to (*insn_write)

Move the check/save of the calib subdevice value to the (*insn_write) function.

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>