[media] pulse8-cec: declare function as static

drivers/staging/media/pulse8-cec/pulse8-cec.c:104:6: warning: no previous prototype for 'pulse8_irq_work_handler' [-Wmissing-prototypes]
 void pulse8_irq_work_handler(struct work_struct *work)
      ^~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/staging/media/pulse8-cec/pulse8-cec.c

@@ -101,7 +101,7 @@ struct pulse8 {
 	bool started;
 };
 
-void pulse8_irq_work_handler(struct work_struct *work)
+static void pulse8_irq_work_handler(struct work_struct *work)
 {
 	struct pulse8 *pulse8 =
 		container_of(work, struct pulse8, work);