bnxt_en: Add ULP calls to stop and restart IRQs.

When the driver needs to re-initailize the IRQ vectors, we make the
new ulp_irq_stop() call to tell the RDMA driver to disable and free
the IRQ vectors.  After IRQ vectors have been re-initailized, we
make the ulp_irq_restart() call to tell the RDMA driver that
IRQs can be restarted.

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