lib/fit_payload: Add coreboot tables support for FDT.

Copy code of depthcharge boot/coreboot.c and adapt it.

Tested on Cavium CN8100 EVB SFF, /sys/firmware/log is readable
and prints the log.

Change-Id: Ib714a021a24f51407558f484cd97aa58ecd43977
Signed-off-by: Philipp Deppenwiese <zaolin@das-labor.org>
Reviewed-on: https://review.coreboot.org/28104
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/include/cbmem.h

@@ -111,6 +111,8 @@ void cbmem_fail_resume(void);
 /* Ramstage only functions. */
 /* Add the cbmem memory used to the memory map at boot. */
 void cbmem_add_bootmem(void);
+/* Return the cbmem memory used */
+void cbmem_get_region(void **baseptr, size_t *size);
 void cbmem_list(void);
 void cbmem_add_records_to_cbtable(struct lb_header *header);