intel/skylake: Implement native Cache-as-RAM (CAR)

Now coreboot should do BIOS CAR setup along with NEM
mode setup.

This patch also provides a mechanism to use 16MB code caching
benefit although LLC still limited to 1M/1.5M based
on SOC LLC limit.
Here with unlimited cache line gets replaced. Now we could use
unlimited cache size along with well defined data size

[pg: updated to current upstream #defines]

BUG=chrome-os-partner:48412
BRANCH=glados
TEST=Builds and Boots on FAB4 SKU2/3.

Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Signed-off-by: pchandri <preetham.chandrian@intel.com>
Signed-off-by: Dhaval Sharma <dhaval.v.sharma@intel.com>

Change-Id: I96a9cf3a6e41cae9619c683dca28ad31dcaa2536
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 2ec51f15c874ad2f1f4fad52fa8deced7b27a24b
Original-Change-Id: Id62c15799d98bc27b5e558adfa7c7b3468aa153a
Original-Reviewed-on: https://chromium-review.googlesource.com/320855
Original-Commit-Ready: Subrata Banik <subrata.banik@intel.com>
Original-Tested-by: Subrata Banik <subrata.banik@intel.com>
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/13138
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/soc/intel/skylake/Kconfig

@@ -176,4 +176,14 @@ config NHLT_SSM4567
 	help
 	  Include DSP firmware settings for ssm4567 smart amplifier.
 
+config DCACHE_RAM_SIZE_TOTAL
+	hex
+	default 0x40000
+
+config SKIP_FSP_CAR
+        bool "Skip cache as RAM setup in FSP"
+        default y
+        help
+          Skip Cache as RAM setup in FSP.
+
 endif