First of all I would ask you if you have enabled I2C on your board first. If you haven't, you can do it with the instructions found on section 11.6 of the Intel® Edison Boards — Intel® Edison Breakout Board Hardware Guide. If you haven't it is very likely that this is the reason why your board doesn't recognize your sensor.
If you have already enabled I2C on your board, then your sensor might not be being recognized since the board should show the sensor's address on a hexadecimal number. In this case, I would test with another I2C sensor to check if the original is not working correctly. It could also be that you are not using the correct voltage reference for your sensor. What's the operational voltage of your sensor?
I can not find section 11.6 in this document? The "Compute Module Hardware Guide" also has no such section?
I think this document is the right one: Intel® Edison Boards — Intel® Edison Kit for Arduino* Hardware Guide
However, section 11.6 refers to I2C_6. I am using I2C_1. Isn't I2C_1 already configured?
On the Arduino breakout board, there are four PCAL95x5-family GPIO expanders on I2C-1, configured on addresses 0x20, 0x21, 0x22, and 0x23. They're used for controlling I/O pin level shifters, pull-up resistors, and analog muxing. The kernel is configured to load the pca953x driver and point it at those addresses. I don't know for certain that that would block other things from using those addresses when not attached to the Arduino board, but it's worth a try to just set your MCP23017's address to something above 0x23.
Alternatively, check if the PCAL9535A or PCAL9555 would work for your application and imitate the Arduino board's configuration. The kernel already knows how to make those appear as /sys/class/gpio/gpio200 to gpio263. You can see how they're set up here: Intel® Edison Boards — Arduino* Board Schematic