msm_mpdecision: make scroff_single_core sysfs parameter functional
  followings are backported from bricked-mako kernel with modifications
  Thanks to showp1984
- added scroff_single_core check to early_suspend and late_resume
- simplified early_suspend and late_resume functions
- added mpdec_cpu_down and mpdec_cpu_up functions to avoid using the same
  code at several places
- cancel workqueue when mpdecision is disabled and use mpdec_cpu_up