block_suspend: avoid CPU spinloop

For verification of blocked suspend or other unit testing, the spinloop
is fine. However, making it sleep so that it is more viable to assist
with power testing or for any other test where avoiding changes to
device performance is important.

Bug: N/A
Test: run, and ps:
root          4179  4168   18720   4724 __se_sys_nanosleep_time32 0 S block_suspend

Change-Id: I81545ae7db1c1fad2cb94d00456d1a6773868111
1 file changed