memory_dff: Recognize read ports with reset / initial value.

tests/memories/read_two_mux.v

@@ -1,6 +1,9 @@
 // expect-wr-ports 1
 // expect-rd-ports 1
-// expect-no-rd-clk
+// expect-rd-clk \clk
+// expect-rd-en \re
+// expect-rd-srst-sig \reset
+// expect-rd-srst-val 8'00000000
 
 module top(input clk, input we, re, reset, input [7:0] addr, wdata, output reg [7:0] rdata);