PM / Sleep: Recommend [un]lock_system_sleep() over using pm_mutex directly
PM / Sleep: Recommend [un]lock_system_sleep() over using pm_mutex directly

Update the documentation to explain the perils of directly using
mutex_[un]lock(&pm_mutex) and recommend the usage of the safe
APIs [un]lock_system_sleep() instead.

Signed-off-by: Srivatsa S. Bhat <5b23f8226e886b22344fc642373ea657dd596b63@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <a11f87183a953ab11f50fbafff689c5a7fa3506c@sisk.pl>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas