cxgb4: fix error return code in adap_init0()

Fix to return a negative error code from the hash filter init error
handling case instead of 0, as done elsewhere in this function.

Fixes: 5c31254e ("cxgb4: initialize hash-filter configuration")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>