Gk20a unmaps the addresses binding to dummy page to clear sparse.
On Gm20b, we need to free the allocated page table entry for sparse
memory.
Bug 1538384
Change-Id: Ie2409ab016c29f42c5f7d97dd7287b093b47f9df
Signed-off-by: Kevin Huang <kevinh@nvidia.com>
Reviewed-on: http://git-master/r/448645
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>