FROMLIST: staging: Android: Add 'vsoc' driver for cuttlefish.

The cuttlefish system is a virtual SoC architecture based on QEMU. It
uses the QEMU ivshmem feature to share memory regions between guest and
host with a custom protocol.

Signed-off-by: Greg Hartman <ghartman@google.com>
[sent upstream via staging https://patchwork.kernel.org/patch/10339507/

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Change-Id: Iaf5d7536898329a66d00764d8892d1395164519e
Signed-off-by: Alistair Strachan <astrachan@google.com>