Silence warnings when converting memories to registers

There are several places where memories are used for parametrization
purposes, but I intend them to be synthesized to registers. Silence
warnings about them by explicitly annotating these variables.

Signed-off-by: Sean Anderson <seanga2@gmail.com>

rtl/hub_core.v

@@ -28,6 +28,7 @@ module hub_core (
 	reg jam, activity;
 	reg [PORT_BITS - 1:0] active_port;
 	reg [PORT_COUNT - 1:0] tx_en_next, tx_er_next;
+	(* mem2reg *)
 	reg [3:0] txd_next [PORT_COUNT - 1:0];
 
 	always @(*) begin

rtl/mii_elastic_buffer.v

@@ -47,6 +47,7 @@ module mii_elastic_buffer (
 
 	integer i;
 	reg [BUF_SIZE - 1:0] valid, valid_next, err, err_next;
+	(* mem2reg *)
 	reg [3:0] data [BUF_SIZE - 1:0], data_next [BUF_SIZE - 1:0];
 	reg shift, overflow_next, underflow_next;
 	reg in, in_next, out, out_next, rx_ce_last, rx_dv_last;