msm: kgsl: Change default pagetable creation sequence

In the existing code, due to dynamic allocation of SMMU
context banks, gfx3d_secure is allotted CB 0 followed by
gfx3d_user with CB 1. This affects per process pagetable
functionality which uses GPU path which updates TTBR0 of
SMMU CB0 by default. This poses issue for targets which
do not have support for Dynamic GPU Aperture programming
in TZ. Move defaultpagetable creation for user context to
kgsl_iommu_init, prior to securepagetable initialization
so that gfx3d_user is allotted CB 0 and gfx3d_secure with
CB 1.

Change-Id: Idf203502281eb2738032425c0132d325fc412094
Signed-off-by: Amit Kushwaha <kushwaha@codeaurora.org>
Signed-off-by: Archana Sriram <apsrir@codeaurora.org>