RDMA/rxe: Fix memory leak in error path code

In rxe_mr_init_user() at the third error the driver fails to free the
memory at mr->map. This patch adds code to do that.  This error only
occurs if page_address() fails to return a non zero address which should
never happen for 64 bit architectures.

Fixes: 8700e3e7 ("Soft RoCE driver")
Link: https://lore.kernel.org/r/20210705164153.17652-1-rpearsonhpe@gmail.com


Reported by: Haakon Bugge <haakon.bugge@oracle.com>
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Reviewed-by: Zhu Yanjun <zyjzyj2000@gmail.com>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>