IB/core: Remove redundant return

"return" statement at the end of void function is redundant, removing
it.

Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Qing Huang <qing.huang@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>