arm64: mm: dma-mapping: fix free of atomic allocation

arm64: mm: dma-mapping: fix free of atomic allocation

Memory allocated from atomic pool is not getting freed and causing
memory leak. The change is fixing it.

Bug 200352333

Change-Id: Id61e283cdae9f2fdd0269d15f399f2dcaff63ebb
Signed-off-by: Pritesh Raithatha <praithatha@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1572923
Reviewed-by: Sachin Nikam <snikam@nvidia.com>
Tested-by: Vidya Sagar <vidyas@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>