gpu: ion: Fix bug in zeroing pages in system heap
gpu: ion: Fix bug in zeroing pages in system heap

Pages are zeroed for security purposes when returned to the
ion heap.  There was a bug in this code preventing this
from happening.

Bug: 7573871
Change-Id: I79c22ee1da98f306199f3a192eaec4e81d5fd059
Signed-off-by: Rebecca Schultz Zavin <0ab09b420c3f4f686e1f6503c93d3111d2038689@android.com>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas