Reset cmd_ready_o in spi_txrx

Initialize bit_count so that cmd_ready_o isn't X state immediately
after reset.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>

spi_rxtx.vhdl

@@ -257,6 +257,9 @@ begin
     count_bit: process(clk)
     begin
         if rising_edge(clk) then
+            if rst = '1' then
+                bit_count <= (others => '0');
+            else
                 if start_cmd = '1' then
                     bit_count <= cmd_clks_i;
                 elsif state /= DATA then
@@ -265,6 +268,7 @@ begin
                     bit_count <= std_ulogic_vector(unsigned(bit_count) - 1);
                 end if;
             end if;
+        end if;
     end process;
 
     -- Shift output data