The problem you will likely run into is that the camera on your phone is porbably integrated into the pcb for the phone. I expect you will be hard pressed to remove it (lens and controller, etc.) in a way that will leave you capable of connecting it to your tablet via usb. I would love to be proven wrong though. After that you will need to either find a driver for that specific camera precompiled or determine how to compile a driver for it. Maybe the camera is supported in v4l, maybe not. You could try running lsmod, lsusb, and lspci on your phone via adb (if it's rooted) to find information on the camera controller.