bnxt_en: Add the ulp_sriov_cfg hooks for bnxt_re RDMA driver.

Add the ulp_sriov_cfg callbacks when the number of VFs is changing.  This
allows the RDMA driver to provision RDMA resources for the VFs.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>