BACKPORT: staging: android: ion: Pull out ion ioctls to a separate file

commit b1fa6d8acb50c8e90f50fb262e5d4b7d478592bf upstream.

The number of Ion ioctls may continue to grow along with necessary
validation. Pull it out into a separate file for easier management
and review.

Signed-off-by: Laura Abbott <labbott@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[nc: Partial backport, only needed for the next commit]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>