vboot2: Look up actual CBFS in MULTIPLE_CBFS configuration

Up to now, the multi-CBFS code path merely looked up files in the "boot
ro" image (ie. the default), disregarding the specified fmap region to
use for CBFS.

The code still relies on the master header being around, which on the
upside allows it to skip an offset at the beginning of the region (eg.
for ARM bootblocks).

This will change later (both the reliance on the master header and the
presence of the bootblock like this).

Change-Id: Ib2fc03eac8add59fc90b4e601f6dfa488257b326
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: http://review.coreboot.org/11805
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/vendorcode/google/chromeos/vboot2/vboot_loader.c

@@ -163,17 +163,7 @@ static int vboot_locate_by_multi_cbfs(const struct region_device *fw_main,
 					struct asset *asset)
 {
 	struct cbfsd cbfs;
-	struct region_device rdev;
-	struct cbfs_props props;
-
-	if (cbfs_boot_region_properties(&props))
-		return -1;
-
-	if (rdev_chain(&rdev, fw_main, props.offset, props.size))
-		return -1;
-
-	cbfs.rdev = &rdev;
-
+	cbfs.rdev = fw_main;
 	return cbfs_locate(asset_rdev(asset), &cbfs, asset_name(asset), NULL);
 }