ARM: tegra: Enable CONFIG_CROS_EC

Updating the tegra_defconfig was omitted, when the ChromeOS EC config
options were renamed by a previous commit. Fix it.

Fixes: 67c70aa8 ("arm/arm64: defconfig: Update configs to use the new CROS_EC options")
Signed-off-by: Maxim Schwalm <maxim.schwalm@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>