ion: revert downstream fix for debugfs synchronization

revert msm specific changes conflicting with commit I3373dc1dbb5
("ion:synchronize debugfs callback and ion_client_destroy")

- revert commit I7bc7562400d ("ion: destroy ion handles under
  client->lock")
- revert commit Ic4c2f9dff90 ("ion: validate ion client in
  ion_debug_client_show() and extract data")
- revert dev->lock usage in ion_debug_heap_show.

Change-Id: Iba5f527b57f39d628b8cd833f627481cc56f6617
Signed-off-by: Prakash Gupta <guptap@codeaurora.org>