IB/qib: Correct qib_verbs_register_sysfs() error handling

qib_verbs_register_sysfs() never cleans up from a failure.
Additionally, the caller of qib_verbs_register_sysfs() doesn't
return the correct "ret" value.

This patch resolves both of those issues.

Reported-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Reviewed-by: Dean Luick <dean.luick@intel.com>

Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/hw/qib/qib_verbs.c b/drivers/infiniband/hw/qib/qib_verbs.c
index 7c0ab16..904c384 100644
--- a/drivers/infiniband/hw/qib/qib_verbs.c
+++ b/drivers/infiniband/hw/qib/qib_verbs.c
@@ -2234,7 +2234,8 @@
 	if (ret)
 		goto err_agents;
 
-	if (qib_verbs_register_sysfs(dd))
+	ret = qib_verbs_register_sysfs(dd);
+	if (ret)
 		goto err_class;
 
 	goto bail;