ANDROID: GKI: scsi: add Android ABI padding to some structures

Try to mitigate potential future driver core api changes by adding a
padding to struct scsi_cmnd, struct scsi_device, and struct
scsi_host_template.

Based on a change made to the RHEL/CENTOS 8 kernel.

Bug: 151154716
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ie6a2b91970e8f9063bf00e96a0dff661f77b8e8d