cr50_fuzz: Disable this fuzz target until chromeos-ec is fixed.
cr50_fuzz: Disable this fuzz target until chromeos-ec is fixed.

BRANCH=None
BUG=chromium:911310
TEST=USE="ubsan asan fuzzer" ./build_packages \
  --board=amd64-generic --skip_chroot_upgrade chromeos-ec

Change-Id: Ib2ffc7035d0f6912834709bb8a5f6b3c11a2c67a
Signed-off-by: Allen Webb <880184b418addffb87cd9c8e8e882ca6764ac96b@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1359652
Reviewed-by: Manoj Gupta <1d49d0f302d724a1dc5fc4d717d15418e9808ddd@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec