dma-buf: Allow disabling deferred unmapping per device

dma-buf: Allow disabling deferred unmapping per device

Use devres framework to allocate a field per device.
If this field is present, disable deferred unmapping.

Do not allow disabling deferred unmapping after dma-buf is
initialized. This way there is no need to handle the
various races that would otherwise have to be handled.

Also, once disabled, do not allow enabling deferred unmapping
again.

bug 1808360

Change-Id: I45fae3389e3f5bc38597284273aab427e8f52e1c
Signed-off-by: Sri Krishna chowdary <schowdary@nvidia.com>
Reviewed-on: http://git-master/r/1220646
GVS: Gerrit_Virtual_Submit
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
Reviewed-by: Sachin Nikam <snikam@nvidia.com>