change its module name.

Change-Id: I646f6d6ac1d678c49548da596858456c3f9ecabb
diff --git a/hdl/verilog/common/dff.sv b/hdl/verilog/common/dff.sv
index 8045e46..1cc7aca 100644
--- a/hdl/verilog/common/dff.sv
+++ b/hdl/verilog/common/dff.sv
@@ -2,7 +2,7 @@
 //   Order of ports is:  q, clk, [rst_n], [e], d
 //   E.g.  DFF #(4) qsig (qsig, clk, rst_n, dsig);
 
-module dffr ( q, clk, rst_n, d ) ; // FF with async rst_n;  
+module dff ( q, clk, rst_n, d ) ; // FF with async rst_n;  
   parameter WIDTH = 1 ;
   input 	clk ;
   input 	rst_n ;