arm: mmap: remove the redundant check of personality

Fixes the merge "Merge tag 'lsk-v3.18-16.04-android' into 'msm-3.18'".
The above mentioned merge wrongly removed part of a fix that was picked
from upstream (arm: factor out mmap ASLR into mmap_rnd). Ressurect the
fix.

Change-Id: Iee77fbec1d2979ea1fa32c0933fd3a22c34a019c
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Imran Khan <kimran@codeaurora.org>