IB/ipoib: Remove unnecessary returned value check

In the function ipoib_set_dev_features, the returned value is always 0.
As such, it is not necessary to check the returned value.
This is not a bug. It is a trivial problem.

Reviewed-by: Guanglei Li <guanglei.li@oracle.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>