ANDROID: GKI: irqdomain.h: add Android ABI padding to a structure

Try to mitigate potential future driver core api changes by adding a
padding to struct irq_domain.

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

Bug: 151154716
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I8ff0c2162ca5f7f0b6c7a51bf341c6b1b1c856e8