lib/coreboot_table: add architecture hooks for adding tables

Add a architecture specific function, arch_write_tables(), that
allows an architecture to add its required tables for booting.
This callback helps write_tables() to be de-duplicated.

Change-Id: I805c2f166b1e75942ad28b6e7e1982d64d2d5498
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/14435
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/arch/riscv/tables.c b/src/arch/riscv/tables.c
index 20891e8..92213c5 100644
--- a/src/arch/riscv/tables.c
+++ b/src/arch/riscv/tables.c
@@ -24,6 +24,10 @@
 #include <cbmem.h>
 #include <lib.h>
 
+void arch_write_tables(uintptr_t coreboot_table)
+{
+}
+
 void bootmem_arch_add_ranges(void)
 {
 }