Add timer and test program

hw/efinix_fpga/addr_decode.sv

@@ -4,11 +4,13 @@ module addr_decode
 
     output o_rom_cs,
     output o_leds_cs,
+    output o_timer_cs,
     output o_sdram_cs
 );
 
 assign o_rom_cs = i_addr >= 16'hf000 && i_addr <= 16'hffff;
 assign o_leds_cs = i_addr == 16'hefff;
+assign o_timer_cs = i_addr >= 16'heff8 && i_addr <= 16'heffe;
 assign o_sdram_cs = i_addr < 16'h8000;
 
 endmodule