Undo Samsung brain-damage to subsystem restart driver

SSR level is supposed to be controlled by sysfs from user space, not
from pre-determined debug level
Also incorporate this change from the Nexus devices
https://www.codeaurora.org/cgit/quic/la/kernel/msm/commit/arch/arm/mach-msm/subsystem_restart.c?h=aosp-new/android-msm-mako-3.4-kitkat-mr2&id=20bfa0b40309bd663b3efab71071cb01311e4696

Change-Id: I42ea4650fcb3920733b6e04c1ef04b5bb598f2ed
Merge "Undo Samsung brain-damage to subsystem restart driver" into cm-11.0