mc2_cn10k_defconfig: Minimal defconfig

This removes all of the unneeded options and puts us on a minimal base
set of options. Some nice to have options may be missing for edge case
uses.

Tested: Ran a bootup, update, and install. Verified USB devices show up
as well as i2c mux + eeproms
Google-Bug-Id: 557296077
Change-Id: Ifc3e2515e16fbd1152ec7f0a103919ff18b08648
Signed-off-by: William A. Kennington III <wak@google.com>