Updated WPFB resource usage for different c_sdp_W_fft_stage_dat = 24b, 25b, 26b. Choose to use 25b.

applications/lofar2/libraries/sdp/src/vhdl/sdp_pkg.vhd

@@ -196,16 +196,20 @@ PACKAGE sdp_pkg is
   --   because the use_separate in the FFT feature does not divide by 2.
   --   This implies that preferrably fft_stage_dat_w <= 26, to fit the 27b
   --   multiplier resources.
-  -- . Increasing fft_stage_dat_w from 24b to 26b does increase M20K usage:
-  --         24b           26b
-  --     FFT 6 x  27 M20K, 6 x  28 M20K, due to separate
-  --     BF  2 x 403 M20K, 2 x 397 M20K, due to reorder_col
+  -- . Resource usage for fft_stage_dat_w = 24b, 25b, 26b:
+  --               24b           25b           26b
+  --     FFT       6 x  27 M20K, 6 x  27 M20K, 6 x  28 M20K, due to separate
+  --     BF        2 x 397 M20K, 2 x 403 M20K, 2 x 403 M20K, due to reorder_col
+  --     u_revison    1738 M20K,    1750 M20K,    1756 M20K,
+  --                    611 DSP,      611 DSP,      611 DSP, same for all
+  --                  332324 FF,    335097 FF,    336262 FF,
   --     where 6 = c_sdp_P_pfb and 2 = c_sdp_N_beamsets.
-  --   The total design increase is 18 m20K = 2.5 % and 4000 FF = 1.2 %. The
-  --   nof DSP remains 611.
+  --   The total increase for u_revison is:
+  --   . for 25b / 24b : 12 m20K = 0.7 % and ~2800 FF = 0.83 %.
+  --   . for 26b / 24b : 18 m20K = 1.0 % and ~4000 FF = 1.2 %.
   CONSTANT c_sdp_W_fil_backoff             : NATURAL := 1;
   CONSTANT c_sdp_W_fft_guard               : NATURAL := 1;
-  CONSTANT c_sdp_W_fft_stage_dat           : NATURAL := 25;  -- TODO try 26b, compare synthesis results
+  CONSTANT c_sdp_W_fft_stage_dat           : NATURAL := 25;
   CONSTANT c_sdp_W_fft_in_dat              : NATURAL := c_sdp_W_fft_stage_dat - c_sdp_W_fft_guard;
   CONSTANT c_sdp_W_fft_out_gain            : NATURAL := 2;
   CONSTANT c_sdp_W_stat_data               : NATURAL := c_sdp_W_subband * 2 + ceil_log2(c_sdp_N_int_sub_hi);  -- = 54