arm64: Lower priority mask for GIC_PRIO_IRQON

arm64: Lower priority mask for GIC_PRIO_IRQON

On a system with two security states, if SCR_EL3.FIQ is cleared,
non-secure IRQ priorities get shifted to fit the secure view but
priority masks aren't.

On such system, it turns out that GIC_PRIO_IRQON masks the priority of
normal interrupts, which obviously ends up in a hang.

Increase GIC_PRIO_IRQON value (i.e. lower priority) to make sure
interrupts are not blocked by it.

Cc: Oleg Nesterov <oleg@redhat.com>
Fixes: bd82d4bd21880b7c ("arm64: Fix incorrect irqflag restore for priority masking")
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Julien Thierry <julien.thierry.kdev@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
[will: fixed Fixes: tag]
Signed-off-by: Will Deacon <will@kernel.org>