Revert "encore defconfigs: disable CONFIG_CC_OPTIMIZE_FOR_SIZE"

This is causing the resulting kernel to fail to boot for some reason.
This almost certainly has to be a gcc bug (and infuriatingly enough, it
works fine with 3.0.8, and also if you just change some of the kernel
config options), but it's holding up the delivery of a critical security
fix, so out it goes.

This reverts commit 3693f33557bb3b9731eff9379a2ab78ea309b078.