- NOTE: This is an optional feature, not built by default. Not included
in the tk1 for sale at Tillitis shop.
- This makes it possible to interface the SPI flash onboard TKey.
- To include the SPI master in the build, use `make application_fpga.bin
YOSYS_FLAG=-DINCLUDE_SPI_MASTER`.
Signed-off-by: Joachim Strömbergson <joachim@assured.se>