ANDROID: GKI: quota.h: add Android ABI padding to some structures

Try to mitigate potential future driver core api changes by adding a
padding to struct quota_format_ops, struct dquot_operations, and struct
quotactl_ops.

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

Bug: 151154716
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ia957d2f8d9b1a6939cddedc16a7481e9de1a8866