ion: add additional debug info in dmabuf exp_info

Add heap name, tgid and comm info to dmabuf export info. This will help
aggregate allocations based of above parameters for debug purpose.

Change-Id: I5d3022ef18f22ec29a87a84d97d64964615b5856
Signed-off-by: Prakash Gupta <guptap@codeaurora.org>