dma-buf: Add support to set a destructor on a dma-buf

dma-buf destructor support is useful as it allows clients an opportunity
to undo any attributes, such as security attributes, they have applied to
the dma-buf's memory.

The destructor is called when the dma-buf is freed, if the destructor
returns an error the dma-buf's exporter release function is not called in
order to ensure that memory which has not been properly cleaned up isn't
returned to the system.

Change-Id: If2173b23b441157b3638110f02e2ff90ab6ad1aa
Signed-off-by: Liam Mark <lmark@codeaurora.org>
Signed-off-by: Swathi Sridhar <swatsrid@codeaurora.org>