drm/msm: update msm gem and smmu for 4.14

This patch fixes some errors when merging downstream 4.9 code with
upstream 4.14 code and addresses issues with holding the global
struct_mutex locks as well as the increase in size of iova variables
from 32-bit to 64-bit values.  Some functions in msm_gem_vma.c were
moved around to improve readability.

Change-Id: I672147376b4c6bead1d775dbbbb4d31b48ac65f4
Signed-off-by: Steve Cohen <cohens@codeaurora.org>