core/conv/conv.c: drop useless assignment

Change-Id: I8c3aa5ec100abacf93da1493aa134e42bf612206
diff --git a/src/conv.c b/src/conv.c
index 8e97e52..b81e37e 100644
--- a/src/conv.c
+++ b/src/conv.c
@@ -624,7 +624,7 @@
 	l = osmo_conv_decode_scan(&decoder, input, code->len);
 
 	if (code->term == CONV_TERM_FLUSH)
-		l = osmo_conv_decode_flush(&decoder, &input[l]);
+		osmo_conv_decode_flush(&decoder, &input[l]);
 
 	rv = osmo_conv_decode_get_output(&decoder, output,
 		code->term == CONV_TERM_FLUSH,		/* has_flush */