Instead disabling interrupts by setting the PSR.I bit, use a priority
higher than the one used for interrupts to mask them via PMR.

When using PMR to disable interrupts, the value of PMR will be used
instead of PSR.[DAIF] for the irqflags.
Signed-off-by: NJulien Thierry <julien.thierry@arm.com>
Suggested-by: NDaniel Thompson <daniel.thompson@linaro.org>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>