ion: Update system heap shrinker to use the new count/scan interface

Update the ION system heap shrinker to use the new count/scan
interfaces that landed in 3.12

Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/staging/android/ion/ion_system_heap.c
Simple merge