soc/intel/{cnl,icl}: Always use CAR NEM enhanced by default

soc/intel/{cnl,icl}: Always use CAR NEM enhanced by default

The FSP_CAR option has additional configuration options whose default
values result in boot failures. Since default values should always boot,
default to the open-source CAR NEM Enhanced implementation instead. This
also allows us to get rid of an unnecessary vendor-specific special case.

Change-Id: I30b1808f91701c07dce6f1de08c213150e8a675a
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34287
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-by: Lean Sheng Tan <lean.sheng.tan@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>