fpga: lib: Fix simulation of axi_fir_filter

The always(*) block was never executing in some simulators because
there were no signals on the right-hand side in the block. Changing it
to an initial block ensures it always runs.


Original-commit: 0b965d579e2df962b91dac141eef6668f932e992

lib/rfnoc/axi_fir_filter.v

@@ -116,7 +116,7 @@ module axi_fir_filter #(
       end
     // Coefficients are static
     end else begin
-      always @(*) begin
+      initial begin
         for (k = 0; k < NUM_SLICES; k = k + 1) begin
           coeffs[k]      <= COEFFS_VEC[COEFF_WIDTH*k +: COEFF_WIDTH];
           coeff_load_stb <= 1'b1;