"default_{xilinx,alter}"

instead of declaring in many places the path to the binary with LM32
software, simply say everywhere "default_altera" or "default_xilinx"
and depending on PCS/simulation settings, pick the proper file at the
board (common) level.

The idea behind aux_diag:
- provide generic mechanism to diagnose application connected to WRPC
  via SNMP
- now, it is used to diagnose WR Streamers and later a user can
  define usage of aux_diag
- it can also happen that aux_diag is used for streamers and user-defined
  application

Thus, the following changes were made:
- diag_id=1 is reserved for wr_streamers
- diag_id=0 is reserved for "not used"
- if the input to board is diag_id=0, and streamers are enabled,
  diag_id is 1 and the aux_diag in/out of WRPC is the one of the
  streamers
- if the input to board is diag_id>1, and streamers are enabled,
  diag_id is the input diag_id and the aux_diag in/out of WRPC is
  concatenation of the diag from streamers and input aux_diag
- if the input ot board is diag_id>1, and streamers are disabled,
  diag_id and aux_diag in/out comes from the user

constrained size of the string that is the input to the function

platform/altera: pass external reference clock through the platform module, in order to match the way this is done in the xilinx platform

platform/altera: update Arria5 PHY with newer version, add default WR PLLs and introduce Altera WR platform wrapper

- Use the built-in 8b10b encoding/decoding provided by the Altera arria5_phy megafunction. This removes the need for
  the custom encoders/decoders, most of the processes at the end of the top-level vhd file, as well as the need for
  the tx_clk_i port and the two generics.

- Repurpose drop_link_i to reset the two megafunctions (arria5_phy_reconf and arria5_phy).

- Removed the Altera clock controllers. The system works fine without them and they only add skew to the clocks.

- Add tx_clk_o port so that we can pass the tx clock to the phy_ref_clk_i of WR PTP core.

- Introduce 8- and 16-bit PCS variants

- Introduce default PLLs for WR:
  * 1x DMTD PLL:  20MHz clock input, 62.5MHz clock output
  * 1x SYS  PLL: 125MHz clock input, 125MHz, 62.5MHz clock outputs
  * 1x EXT  PLL:  10MHz clock input, 125MHz clock output

- Reset all blocks properly and make sure that phy_ready is syncrhonised to phy_rx_clk

wrc.bram compiled from commit (wrpc-sw repo):
61dfdc2 wrpc sim: missing pl_cnt assignment

for details how it works now.

Short description of changes
- frames are generated in two places: LM32 and main.sv
- frames from LM32 are looped back in main.sv
- frames from main.sv go through WRPC and are looped back by wrf_loopback
- frames generated by main.sv have randome size, Inter-frame gap
  is randome for one bunch of sent frames, and fixed low for stress
  in another bunch of sent frames.
- frames from LM32 are sent as fast as possible, which is sloooow
- frames from LM32 have codes to indicate to the simulation problems
  of reception of previous frame (no other easy way for information
  to pass from LM32 to main.sv
- all frames have seqID which is verified in main.sv
- warnings are thrown when
  * wrong seqID is detected by main.sv
  * when ERROR code is sent by LM32, can be on seqID mismatch, or
    rx function error

NOTE: the software for LM32 is now compiled by proper make config
in wrpc-sw (see wrpc-sw/config): wrpc_sim_defconfig

the script

NOTE: you need to run make before do run.do ...