Intel cpus: copy model_6ex CAR code

Copy model_6ex CAR as car/cache_as_ram_ht.inc to be extended
with hyper-threading CPU support.

Change-Id: I09619363e714b1ebf813932b0b22123c1d89010e
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/606
Tested-by: build bot (Jenkins)
Reviewed-by: Idwer Vollering <vidwer@gmail.com>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>