staging: comedi: rti800: change return of rti800_ai_insn_read()

The comedi core expects the (*insn_read) functions to return the
number of data values actually read. Change the return from 'i'
to 'insn->n' to make this clearer.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/rti800.c

@@ -223,7 +223,7 @@ static int rti800_ai_insn_read(struct comedi_device *dev,
 			data[i] ^= 0x800;
 	}
 
-	return i;
+	return insn->n;
 }
 
 static int rti800_ao_insn_read(struct comedi_device *dev,