sound: oss: remove last sleep_on users

There are three files in oss for which I could not find an easy way to
replace interruptible_sleep_on_timeout with a non-racy version. This
patch instead just adds a private implementation of the function, now
named oss_broken_sleep_on, and changes over the remaining users in
sound/oss/ so we can remove the global interface.

[fixed coding style warnings by tiwai]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>