Use tcl script instead of static xmls for the interface.
Easier to maintain and are not gitignored.
Rename spi_master to spi_engine because every interface should be
prefixed by the IP name; in this case, spi_engine.
Also, remove interface/*.sv files on make clean and git ignore them.
Signed-off-by: Jorge Marques <jorge.marques@analog.com>
e2ca5a991a