soc/intel/common: remove mrc cache assumptions

Update the mrc cache implementation to use region_file. Instead
of relying on memory-mapped access and pointer arithmetic
use the region_devices and region_file to obtain the latest
data associated with the region. This removes the need for the
nvm wrapper as the region_devices can be used directly. Thus,
the library is more generic and can be extended to work on
different boot mediums.

BUG=chrome-os-partner:56151

Change-Id: Ic14e2d2f7339e50256b4a3a297fc33991861ca44
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/17717
Tested-by: build bot (Jenkins)
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

src/soc/intel/apollolake/mmap_boot.c

@@ -23,7 +23,6 @@
 #include <console/console.h>
 #include <fmap.h>
 #include <soc/flash_ctrlr.h>
-#include <soc/intel/common/nvm.h>
 #include <soc/mmap_boot.h>
 
 /*
@@ -148,22 +147,6 @@ const struct cbfs_locator cbfs_master_header_locator = {
 	.locate = iafw_boot_region_properties,
 };
 
-uint32_t nvm_mmio_to_flash_offset(void *p)
-{
-	bios_mmap_init();
-
-	size_t start, size;
-	start = car_get_var(bios_start);
-	size = car_get_var(bios_size);
-
-	/*
-	 * Returns :
-	 * addr - base of mmaped region in addr space + offset of mmaped region
-	 * start on flash
-	 */
-	return (uintptr_t)p - (4ULL * GiB - size) + start;
-}
-
 size_t get_bios_size(void)
 {
 	bios_mmap_init();