pcs: tx: Calculate idle correctly when there is no new data

When the PMA has no new data for us, idle should be determined based on
raw_bits[11:2]. However, we just calculated that last cycle, so we can
reuse it.

Fixes: d351291 ("Initial commit")
Signed-off-by: Sean Anderson <seanga2@gmail.com>

rtl/pcs.v

@@ -334,6 +334,8 @@ module pcs_rx_bits (
 	endfunction
 
 	always @(*) begin
+		idle_next = idle;
+		if (bits_valid != 0)
 			idle_next = &raw_bits[10:1];
 		if (bits_valid & 2)
 			idle_next = idle_next || &raw_bits[9:0];