irqchip/gic-v3-its: Give the percpu rdist struct its own flags field

commit eba1e44b

 upstream

Later patches will require tracking some per-rdist status. Reuse the bytes
"lost" to padding within the __percpu rdist struct as a flags field, and
re-encode ->lpi_enabled within said flags.

No change in functionality intended.

Stable backport notes:
Backport this patch, because this 0002 patch that fixs a calltrace
issue of sleeping function called from invalid context is based on it.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211027151506.2085066-2-valentin.schneider@arm.com
Signed-off-by: Meng Li <Meng.Li@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>