ixgbe: fix sparse warning

error: bad constant expression

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Evan Swanson <evan.swanson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ixgbe/ixgbe_sriov.c

@@ -324,7 +324,7 @@ static inline void ixgbe_vf_reset_msg(struct ixgbe_adapter *adapter, u32 vf)
 static int ixgbe_rcv_msg_from_vf(struct ixgbe_adapter *adapter, u32 vf)
 {
 	u32 mbx_size = IXGBE_VFMAILBOX_SIZE;
-	u32 msgbuf[mbx_size];
+	u32 msgbuf[IXGBE_VFMAILBOX_SIZE];
 	struct ixgbe_hw *hw = &adapter->hw;
 	s32 retval;
 	int entries;