ixgbe: Check for fw_recovery

The x550 uses an upgradable flash code.  Check for recovery condition
like other flashable intel cards do in case of fw errors.

MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D31869

sys/dev/ixgbe/if_ix.c

@@ -919,6 +919,15 @@ ixgbe_if_attach_pre(if_ctx_t ctx)
 		goto err_pci;
 	}
 
+	if (hw->mac.ops.fw_recovery_mode && hw->mac.ops.fw_recovery_mode(hw)) {
+		device_printf(dev, "Firmware recovery mode detected. Limiting "
+		    "functionality.\nRefer to the Intel(R) Ethernet Adapters "
+		    "and Devices User Guide for details on firmware recovery "
+		    "mode.");
+		error = ENOSYS;
+		goto err_pci;
+	}
+
 	if (hw->mbx.ops.init_params)
 		hw->mbx.ops.init_params(hw);