Fix some errors

j-2.ref.txt fixed and removed square bracket from regfile

inputs/j/j-2.ref.txt

@@ -1 +1 @@
-3
+2

rtl/mips_cpu_regfile.v

@@ -48,7 +48,7 @@ always_ff @(negedge clk) begin
 				endcase // readdata1[1:0]
 			end
 			6'b100001: begin //lh, load half-word
-				case (vaddr]) // must be half-word aligned, readdata1[0] = 0
+				case (vaddr) // must be half-word aligned, readdata1[0] = 0
 					2'b00: memory[writereg] <= {{16{writedata[15]}}, writedata[15:0]};
 					2'b10: memory[writereg] <= {{16{writedata[31]}}, writedata[31:16]};
 				endcase // readdata1[1:0]