msm: lmh_lite: Add memory barrier before reading data from trustzone

Add memory barrier before reading data from trustzone
to make sure LMH driver doesnt fails because of
reading the data in out of order execution.

CRs-Fixed: 759855
Change-Id: Id2e917bf8100fc2f775186d8db630a39089337a2
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>