IB/rxe: avoid unnecessary export

The function rxe_remove_all is only used in this modules.
There is no other modules that call this function. So it
is not necessary to export it.

Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>