meson: Add meson build system

Allow building the driver with meson. Could probably use
plenty of cleanups, but at least it gives me a working driver.
And I think I managed to make it build everything that
autotools builds.

Quite a few compiler warnings were suppressed as well. Might
want to look at those at some point.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>