staging: android: ion: Remove struct ion_platform_heap

Now that ION heap registration has been re-worked to not depend on board
files or have a central heap register helper there is no need to have
this data structure. Most of the fields are unused.

Some heap creation helpers are still available that use this to define
the a heap but only use 2 or 3 elements from this struct, just convert
these to get supplied these values from the heap registrar directly.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>