kunit: debugfs: Fix unchecked dereference in debugfs_print_results()

Move the call to kunit_suite_has_succeeded() after the check that
the kunit_suite pointer is valid.

This was found by smatch:

 lib/kunit/debugfs.c:66 debugfs_print_results() warn: variable
 dereferenced before check 'suite' (see line 63)

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: 38289a26 ("kunit: fix debugfs code to use enum kunit_status, not bool")
Reviewed-by: Rae Moar <rmoar@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>