Nokia N900: Implement pcm_play_lock() / pcm_play_unlock()

Shamelessly stolen from pcm-android.c

Thanks to Michael Sevakis for pointing out
that pcm_play_lock() is actually needed.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31190 a1c6a512-1295-4272-9138-f99709370657
1 file changed