[PATCH] pmac: save master volume on sleep

Ben's patch that shutdowns master switch and restores it after resume
("pmac: Improve sleep code of tumbler driver") isn't enough here on an
iBook (snapper chip).

The master switch is correctly saved and restored, but somehow
tumbler_put_master_volume() gets called just after
tumbler_set_master_volume() and sets mix->master_vol[*] to 0.  So, on
resuming, the master switch is reenabled, but the volume is set to 0.

Here's a patch that also saves and restores master_vol.

Signed-off-by: Colin Leroy <colin@colino.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>