tests: watchdog: Debug for boards enabled TEST_WDT_CALLBACK_2

The original code cannot go to the next step on those boards enabled
TEST_WDT_CALLBACK_2 macro, because of the flow control issue. So the
test function cannot finish, and the board keeps restart. As a result,
failure on the test.

Fixes #13468

Signed-off-by: Aaron Tsui <aaron.tsui@outlook.com>
1 file changed