msm: kgsl: Check MMU type for memory and pagetable operations

Check MMU type for below operations to make NOMMU functional:

- adreno_iommu_set_pt_ctx() tries to set pagetable during context
  switch without really checking on type of MMU.
- skip tracking of gpuaddr in case of NoMMU during
  kgsl_mem_entry_track_gpuaddr().
- In case of nommu the function kgsl_allocate_global() should
  always allocate contiguous memory from CMA.

Change-Id: I8cb59e1475376167c7a8a60c54df0939597f5083
Signed-off-by: Rajesh Kemisetti <rajeshk@codeaurora.org>