KVM: arm64: Map SVE context at EL2 when available

mainline inclusion
from mainline-v5.13-rc1
commit 0a9a98fd
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8E73O
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0a9a98fda3a24b0775ace4be096290b221f2f6a5



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

When running on nVHE, and that the vcpu supports SVE, map the
SVE state at EL2 so that KVM can access it.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>