enic: enic_ethtool: fix sparse warning

this patch fixes following sparse warning:

enic_ethtool.c:95:6: warning: symbol 'enic_intr_coal_set_rx' was not declared. Should it be static?
Signed-off-by: NLad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/cisco/enic/enic_ethtool.c

@@ -92,7 +92,7 @@ static const unsigned int enic_n_tx_stats = ARRAY_SIZE(enic_tx_stats);
 static const unsigned int enic_n_rx_stats = ARRAY_SIZE(enic_rx_stats);
 static const unsigned int enic_n_gen_stats = ARRAY_SIZE(enic_gen_stats);
 
-void enic_intr_coal_set_rx(struct enic *enic, u32 timer)
+static void enic_intr_coal_set_rx(struct enic *enic, u32 timer)
 {
 	int i;
 	int intr;