how to make i2c-core as module

Hello I have beagleboneblack board and have kernel source code I want to make my i2c work as a module so for that, I have done some changes in .config file

## I2C support#CONFIG_I2C=m

and cross compile kernel

make dtbs zImage -j8 CROSS_COMPILE=arm-linux-gnueabihf- 

But after compile successfully, CONFIG_I2C change from 'm' to 'y'how to solve this problem?