[ALSA] Fix-up sleeping in sound/ppc

PPC AWACS driver,PPC PMAC driver,PPC Tumbler driver
Description: Fix-up sleeping in sound/ppc. Replace big_mdelay() with
msleep() to guarantee the task delays as expected. This also involved
replacing/removing custom sleep functions.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>