sandbox: add get_{tbclk,ticks}

Fixes building after recent readline updates with timeouts.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

board/sandbox/sandbox/sandbox.c

@@ -34,6 +34,16 @@ void flush_cache(unsigned long start, unsigned long size)
 {
 }
 
+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;