cpu_affinity: restore the original cpu affinity correctly [1/1]

cpu_affinity: restore the original cpu affinity correctly [1/1]

PD#SWPL-5595

Problem:
set_cpus_allowed_ptr(current, cpu_all_mask) is always errorly
called to retore CPU affinity for current task. In some cases,
the current may be a bounded kworker thread, and we should not
set its CPU affinity to all CPUs

Solution:
Save the original CPU affinity and restore it

Verify:
W400 revB

Change-Id: I3cd65e79791563af9dacc09639b8645b97979c44
Signed-off-by: Jiamin Ma <jiamin.ma@amlogic.com>