sandbox: add get_{tbclk,ticks}

Fixes building after recent readline updates with timeouts.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/board/sandbox/sandbox/sandbox.c b/board/sandbox/sandbox/sandbox.c
index f376c74..9883013 100644
--- a/board/sandbox/sandbox/sandbox.c
+++ b/board/sandbox/sandbox/sandbox.c
@@ -34,6 +34,16 @@
 {
 }
 
+ulong get_tbclk(void)
+{
+	return CONFIG_SYS_HZ;
+}
+
+unsigned long long get_ticks(void)
+{
+	return get_timer(0);
+}
+
 ulong get_timer(ulong base)
 {
 	return (os_get_nsec() / 1000000) - base;