lib/coreboot_table: add function to allow arch code to add records

Add lb_arch_add_records() to allow the architecture code to
generically hook into the coreboot table generation.

BUG=chrome-os-partner:50214
BRANCH=glados
TEST=With all subsequent patches confirmed lb_arch_add_records() is
     called when a strong symbol is provided.

Change-Id: I7c69c0ff0801392bbcf5aef586a48388b624afd4
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/13669
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>

src/lib/coreboot_table.c

@@ -540,6 +540,9 @@ unsigned long write_coreboot_table(
 
 	lb_boot_media_params(head);
 
+	/* Add architecture records. */
+	lb_arch_add_records(head);
+
 	/* Add all cbmem entries into the coreboot tables. */
 	cbmem_add_records_to_cbtable(head);