ixgbe: fix static functions

Define functions as static added C=1 (sparse) to my make line
brought these to my attention.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ixgbe/ixgbe_main.c b/drivers/net/ixgbe/ixgbe_main.c
index dbe29e5..227a9b4 100644
--- a/drivers/net/ixgbe/ixgbe_main.c
+++ b/drivers/net/ixgbe/ixgbe_main.c
@@ -4566,8 +4566,8 @@
 #ifdef CONFIG_IXGBE_DCB
 
 /* ixgbe_get_first_reg_idx - Return first register index associated with ring */
-void ixgbe_get_first_reg_idx(struct ixgbe_adapter *adapter, u8 tc,
-			     unsigned int *tx, unsigned int *rx)
+static void ixgbe_get_first_reg_idx(struct ixgbe_adapter *adapter, u8 tc,
+				    unsigned int *tx, unsigned int *rx)
 {
 	struct net_device *dev = adapter->netdev;
 	struct ixgbe_hw *hw = &adapter->hw;