ixgbe: Do not clear RAR entry when clearing VMDq for SAN MAC

The RAR entry for the SAN MAC address was being cleared when we were
clearing the VMDq pool bits.  In order to prevent this we need to add
an extra check to protect the SAN MAC from being cleared.

Fixes: 6e982aea ("ixgbe: Clear stale pool mappings")
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>