The driver has always had a FIXME about this, and it seems
like this trivial code move avoids a mach header inclusion,
so just do it.

With that out of the way, and the header file inclusions
changed to global files, the driver can also be compile-tested
on other platforms.
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>