pata_sil680: make sil680_sff_exec_command() 'static'

... since, of course, it's not used outside this driver.
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/pata_sil680.c

@@ -202,7 +202,7 @@ static void sil680_set_dmamode(struct ata_port *ap, struct ata_device *adev)
  *	LOCKING:
  *	spin_lock_irqsave(host lock)
  */
-void sil680_sff_exec_command(struct ata_port *ap,
+static void sil680_sff_exec_command(struct ata_port *ap,
 				    const struct ata_taskfile *tf)
 {
 	DPRINTK("ata%u: cmd 0x%X\n", ap->print_id, tf->command);