video:tegra:nvmap: defer virtual space free till handle free

video:tegra:nvmap: defer virtual space free till handle free

Remappings are expensive operation and should be avoided.

Create a single virtual mapping on first cache maintenance or
mapping request and reuse it until memory buffer is destroyed.

Do not enable this optimization on 32bit platforms because
of limited vmalloc space.

bug 1460266

Change-Id: Ib9361ec779f3e529c79a97e60dd6e3ae55c0a7d4
Signed-off-by: Kirill Artamonov <kartamonov@nvidia.com>
Reviewed-on: http://git-master/r/379316
Reviewed-by: Krishna Reddy <vdumpa@nvidia.com>
Tested-by: Krishna Reddy <vdumpa@nvidia.com>