drivers/net/skfp: fix sparse warnings: make symbols static

Fix this sparse warnings:

  drivers/net/skfp/skfddi.c:620:13: warning: symbol 'skfp_interrupt' was not declared. Should it be static?
  drivers/net/skfp/skfddi.c:687:25: warning: symbol 'skfp_ctl_get_stats' was not declared. Should it be static?
  drivers/net/skfp/skfddi.c:1232:6: warning: symbol 'CheckSourceAddress' was not declared. Should it be static?
Signed-off-by: NHannes Eder <hannes@hanneseder.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/skfp/skfddi.c

@@ -617,7 +617,7 @@ static int skfp_close(struct net_device *dev)
  *   Interrupts are disabled, then reenabled at the adapter.
  */
 
-irqreturn_t skfp_interrupt(int irq, void *dev_id)
+static irqreturn_t skfp_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = dev_id;
 	struct s_smc *smc;	/* private board structure pointer */
@@ -684,7 +684,7 @@ irqreturn_t skfp_interrupt(int irq, void *dev_id)
  *   independent.
  *
  */
-struct net_device_stats *skfp_ctl_get_stats(struct net_device *dev)
+static struct net_device_stats *skfp_ctl_get_stats(struct net_device *dev)
 {
 	struct s_smc *bp = netdev_priv(dev);
 
@@ -1229,7 +1229,7 @@ static void send_queued_packets(struct s_smc *smc)
  * Verify if the source address is set. Insert it if necessary.
  *
  ************************/
-void CheckSourceAddress(unsigned char *frame, unsigned char *hw_addr)
+static void CheckSourceAddress(unsigned char *frame, unsigned char *hw_addr)
 {
 	unsigned char SRBit;