test_objagg: Fix potential memory leak in error handling

commit a6379f0a upstream.

In case of failure of check_expect_hints_stats(), the resources
allocated by objagg_hints_get should be freed. The patch fixes
this issue.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>