staging: android: ion: Remove import interface

With the expansion of dma-buf and the move for Ion to be come just an
allocator, the import mechanism is mostly useless. There isn't a kernel
component to Ion anymore and handles are private to Ion. Remove this
interface.

Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>