libpayload: Implement new CBFS access API

This commit adds new CBFS API, which is based on the one available in
the main coreboot source tree. Libpayload implementation supports RO/RW
file lookups and file contents verification.

Change-Id: I00da0658dbac0cddf92ad55611def947932d23c7
Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59497
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

payloads/libpayload/libcbfs/Kconfig

@@ -0,0 +1,31 @@
+## SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-or-later
+
+config CBFS
+	bool "CBFS support"
+	default y
+	help
+	  CBFS is the archive format of coreboot
+
+if CBFS
+
+config DEBUG_CBFS
+	bool "Output verbose CBFS debug messages"
+	default n
+	help
+	  This option enables additional CBFS related debug messages.
+
+config ENABLE_CBFS_FALLBACK
+	bool "Fallback to RO (COREBOOT) region"
+	default n
+	help
+	  When this option is enabled, the CBFS code will look for a file in the
+	  RO (COREBOOT) region, if it isn't available in the active RW region.
+	  This option makes sense only if CONFIG_VBOOT was enabled in the coreboot.
+
+config CBFS_VERIFICATION
+	bool "Enable CBFS verification"
+	depends on VBOOT
+	help
+	  This option enables hash verification of CBFS files in RO (COREBOOT) and RW regions.
+
+endif