[media] dib9000: get rid of warning: no previous prototype

drivers/media/dvb-frontends/dib9000.h:100:5: warning: no previous prototype for 'dib9000_remove_slave_frontend' [-Wmissing-prototypes]

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/dvb-frontends/dib9000.h b/drivers/media/dvb-frontends/dib9000.h
index b5781a4..de1cc91 100644
--- a/drivers/media/dvb-frontends/dib9000.h
+++ b/drivers/media/dvb-frontends/dib9000.h
@@ -97,7 +97,7 @@
 	return -ENODEV;
 }
 
-int dib9000_remove_slave_frontend(struct dvb_frontend *fe)
+static inline int dib9000_remove_slave_frontend(struct dvb_frontend *fe)
 {
 	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
 	return -ENODEV;