irqchip/gic-v3-its: Fix ITT_entry_size accessor

irqchip/gic-v3-its: Fix ITT_entry_size accessor

BugLink: https://bugs.launchpad.net/bugs/1837813
[ Upstream commit 56841070ccc87b463ac037d2d1f2beb8e5e35f0c ]

According to ARM IHI 0069C (ID070116), we should use GITS_TYPER's
bits [7:4] as ITT_entry_size instead of [8:4]. Although this is
pretty annoying, it only results in a potential over-allocation
of memory, and nothing bad happens.

Fixes: 3dfa576bfb45 ("irqchip/gic-v3-its: Add probing for VLPI properties")
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
[maz: massaged subject and commit message]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>