Converting the Makefile to use the new tools buildsystem.

Signed-off-by: Heikki Krogerus
[fixes builds with O=...]
Reviewed-by: Andy Shevchenko
Link: https://lore.kernel.org/r/20200819071733.60028-1-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman