mms152_ts/gestures: add gesture booster (dvfs) and sysfs entries

add a dvfs lock when a gesture is recognized to speed up its processing.

/sys/devices/virtual/misc/touch_gestures/gesturebooster_enabled
  - enable the gesture booster.

/sys/devices/virtual/misc/touch_gestures/gesturebooster_freq
  - frequency to boost to. 0 will autodetect policy->max.

/sys/devices/virtual/misc/touch_gestures/gesturebooster_duration
  - how long to hold the boost for.