staging: olpc_dcon: Remove unnecessary externs

Using 'extern' is not necessary for function prototypes.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/olpc_dcon/olpc_dcon.h

@@ -98,7 +98,7 @@ struct dcon_platform_data {
 
 #include <linux/interrupt.h>
 
-extern irqreturn_t dcon_interrupt(int irq, void *id);
+irqreturn_t dcon_interrupt(int irq, void *id);
 
 #ifdef CONFIG_FB_OLPC_DCON_1
 extern struct dcon_platform_data dcon_pdata_xo_1;