[HW] Removed (unnecessary) initial value for TX buffer

Makes Synplify for iCE40 want to implement buffer in RAM but then fail
due to reset.

hw/rtl/fault_injection_tx_buffer_rtl.vhd

@@ -32,7 +32,7 @@ architecture rtl of fault_injection_tx_buffer is
 
   -- cb memory
   type t_cb_storage is array (g_buffer_depth-1 downto 0) of std_logic_vector(g_buffer_width-1 downto 0);
-  signal s_cb_storage : t_cb_storage := (others => (others => '0'));
+  signal s_cb_storage : t_cb_storage;
 
   -- the MSB is used to count how often the respective pointers wrapped modulo 2
   -- i.e. if they are still in the same "round"