hotplug/shpchp_hpc: replace

I would appreciate any comments from the janitors list. This is one (of many) cases where I made a decision about replacing

set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(some_time);

with

msleep(jiffies_to_msecs(some_time));

msleep() is not exactly the same as the previous code, but I only did this replacement where I thought long delays were *desired*. If this is not the case here, then just disregard this patch.