lattice_crosslink_nx_evn: don't set MASTER_SPI_PORT=SERIAL

Setting MASTER_SPI_PORT=SERIAL causes the SPI flash pins to be reserved
for use by the sysCONFIG logic, and prevents user logic from assigning
them. This made it impossible to have a Litex design which accesses the
SPI flash on this board.

Remove the setting, so that we get the default behaviour which permits
user logic to assign these pins. In the unlikely event that someone
needs the pins to stay reserved for sysCONFIG after configuration (I'm
not sure why this would be needed) they could explicitly add this
command in their design.

lattice_crosslink_nx_evn: allow specifying the FPGA device

- Now uses regular UART.
- Build tested with: ./quertyembedded_beaglewire.py --cpu-type=serv --build
- Can still be build with Crossover UART with --uart-name=crossover+bridge.

beaglewire platform and target added

WIP: Initial PYNQ Z2 support

FIX: OrangeCrab Feather SPI pad name

ebaz4205: Remove PS7 support for now (since untested and we'll avoid the .xci in LiteX-Boards repository).

Usage:

```
./ebaz4205.py --cpu-type=vexriscv --build --load
```

```
$ pwd
litex-boards/litex_boards/targets
```

Tip: Use `GTKTerm` to connect to /dev/ttyUSB0 (usually) and interact
with the LiteX BIOS.

References:

- https://github.com/fusesoc/blinky#ebaz4205-development-board
- https://github.com/olofk/serv/#ebaz4205-development-board
- https://github.com/xjtuecho/EBAZ4205#ebaz4205
- https://github.com/nmigen/nmigen-boards/pull/180 (merged)
- https://github.com/olofk/corescore/pull/33
- The existing 'Zybo Z7' example

Note: The `PS7` stuff remains untested via LiteX for now.

**Problems**

`SPIMaster` pad names are `clk`, `cs_n`, `mosi`, and `miso`.
However, `feather_spi` is using `sck` instead of `clk`, therefore
it is not able to use as-is for `SPIMaster`, for example,
with `add_spi` on Linux On LiteX VexRiscv.

**Solution**

In fact, `spisdcard` and other SPI related pad names are
using `clk`, only `feather_spi` is using `sck`.
Therefore, rename `sck` to `clk`.

This board is documented as having the LIFCL-40-9BG400C part, but some
versions of the board exist which were fitted with LIFCL-40-8BG400CES,
an engineering sample part. The distinction is important because the
engineering sample requires a different device ID to be embedded in the
bitstream. If you try to build a bitstream for LIFCL-40-9BG400C and load
it onto LIFCL-40-8BG400CES the configuration fails (indicated by the red
"INITN" LED on this board).

Accept --device to allow the user to specify which FPGA part their board
has.

update IRC channel in README

colorlight_5a_75x: Disable full_memory_we for l2 cache by default

Leads to an increase in DP16KD, first noticed in
https://github.com/enjoy-digital/liteeth/issues/70.
With full_mem_we:
```
Info: 	              DP16KD:    41/   56    73%
```
Without:
```
Info: 	              DP16KD:    29/   56    51%
```

targets: Remove old call to add_spi_flash on targets now using LiteSPI (we'll find it with gitk is required).

Add option for different Fomu SPI ICs.

Signed-off-by: Joey Bushagour <jbushagour@google.com>

This is now required since ECP5PLL now checks that PFD is in required range.