PM / sleep: Simplify sleep states sysfs interface code

Simplify the sleep states sysfs interface /sys/power/state code by
redefining pm_states[] as an array of pointers to constant strings
such that only the entries corresponding to valid states are set.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --cc kernel/power/main.c
Simple merge

diff --cc kernel/power/power.h
Simple merge

diff --cc kernel/power/suspend.c
Simple merge

diff --cc kernel/power/suspend_test.c
Simple merge