ixgbe: Return error on failure to allocate mac_table

Add a check to make certain mac_table was actually allocated and is not
NULL.  If it is NULL return -ENOMEM and allow the probe routine to fail
rather then causing a NULL pointer dereference further down the line.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -5381,6 +5381,8 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter)
 	adapter->mac_table = kzalloc(sizeof(struct ixgbe_mac_addr) *
 				     hw->mac.num_rar_entries,
 				     GFP_ATOMIC);
+	if (!adapter->mac_table)
+		return -ENOMEM;
 
 	/* Set MAC specific capability flags and exceptions */
 	switch (hw->mac.type) {