test: Add the beginnings of some string tests

There are quite a few string functions in U-Boot with no tests. Make a
start by adding a test for strtoul().

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/test/suites.h b/include/test/suites.h
index 39ad81a..213e3ce 100644
--- a/include/test/suites.h
+++ b/include/test/suites.h
@@ -33,6 +33,7 @@
 int do_ut_log(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
 int do_ut_optee(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
 int do_ut_overlay(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
+int do_ut_str(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[]);
 int do_ut_time(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
 int do_ut_unicode(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);