ANDROID: delete ION code

Upstream commit e722a295 ("staging: ion: remove from the tree")
removes the ION code from the kernel tree, but the version of ION that
is in the ANDROID tree is a bit more complex and different.  To make it
"easier" if someone needs to bring the ION code back, revert it all
here, in this commit, so that when the upstream merge happens, the
deletion is not burried in a merge commit.

Fixes: e722a295 ("staging: ion: remove from the tree")
Cc: Hridya Valsaraju <hridya@google.com>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ibd9332f5878879579508c947976d943d1fd6023a