cbfs: Stop checking master header

The CBFS master header is a legacy structure that just conveys the same
information we already have from the FMAP these days. We're still
including it to support older CBFS implementations in some payloads, but
there's no need for coreboot itself to follow this indirection anymore.
This patch simplifies the default CBFS locator to just return the CBFS
offset and size from the FMAP directly.

Change-Id: I6b00dd7f276364d62fa1f637efbaee0e80607c49
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36688
Reviewed-by: Wim Vervoorn <wvervoorn@eltan.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/vendorcode/eltan/security/verified_boot/vboot_check.c

@@ -355,8 +355,8 @@ static void vendor_secure_prepare(void)
 	}
 }
 
-const struct cbfs_locator cbfs_master_header_locator = {
+const struct cbfs_locator cbfs_default_locator = {
 	.name = "Vendorcode Header Locator",
 	.prepare = vendor_secure_prepare,
-	.locate = cbfs_master_header_props
+	.locate = cbfs_default_props
 };