arm64: Relax GIC version check during early boot

mainline inclusion
from mainline-5.0
commit 74698f69
category: bugfix
bugzilla: 10793
CVE: NA

-------------------------------------------------

Updates to the GIC architecture allow ID_AA64PFR0_EL1.GIC to have
values other than 0 or 1. At the moment, Linux is quite strict in the
way it handles this field at early boot stage (cpufeature is fine) and
will refuse to use the system register CPU interface if it doesn't
find the value 1.

Fixes: 021f6537 ("irqchip: gic-v3: Initial support for GICv3")
Reported-by: Chase Conklin <Chase.Conklin@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Xuefeng Wang <wxf.wang@hisilicon.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>