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

drivers/media/common/siano/smscoreapi.c:1095:26: warning: no previous prototype for 'get_entry' [-Wmissing-prototypes]
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/common/siano/smscoreapi.c

@@ -1092,7 +1092,7 @@ EXPORT_SYMBOL_GPL(smscore_onresponse);
  * @return pointer to descriptor on success, NULL on error.
  */
 
-struct smscore_buffer_t *get_entry(struct smscore_device_t *coredev)
+static struct smscore_buffer_t *get_entry(struct smscore_device_t *coredev)
 {
 	struct smscore_buffer_t *cb = NULL;
 	unsigned long flags;