This patch fixes the following gcc warning:
drivers/base/power/domain.c: In function ‘genpd_runtime_resume’:
drivers/base/power/domain.c:642:14: warning: ‘time_start’ may be used
uninitialized in this function [-Wmaybe-uninitialized]
   elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start)
The same problem (in another function in this same file) was fixed in
commit 
d33d5a6c88fc (avoid spurious "may be used uninitialized" warning)
Signed-off-by: Augusto Mecking Caringi <augustocaringi@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 
 
  out:
        /* Measure resume latency. */
+       time_start = 0;
        if (timed && runtime_pm)
                time_start = ktime_get();