Remove duplicate line of code

Change-Id: Ie92a17d6c530bdd65464fbc599ce92561b8c0428
diff --git a/av1/encoder/firstpass.h b/av1/encoder/firstpass.h
index 3737f62..7c948a5 100644
--- a/av1/encoder/firstpass.h
+++ b/av1/encoder/firstpass.h
@@ -194,7 +194,6 @@
 
 void av1_init_second_pass(struct AV1_COMP *cpi);
 void av1_rc_get_second_pass_params(struct AV1_COMP *cpi);
-void av1_twopass_postencode_update(struct AV1_COMP *cpi);
 
 // Post encode update of the rate control parameters for 2-pass
 void av1_twopass_postencode_update(struct AV1_COMP *cpi);