mlx4_core: adjust catas operation for SRIOV mode

When running in SRIOV mode, driver should not automatically start/stop
the mlx4_core upon sensing an HCA internal error -- doing this disables/enables
sriov, which will cause the hypervisor to hang if there are running VMs with
attached VFs.

In addition, on VMs the catas process should not run at all, since the HCA
error buffer is not available to VMs in the BARs.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>