arm64: sve: Provide sve_cond_update_zcr_vq fallback when !ARM64_SVE

mainline inclusion
from mainline-v5.13-rc1
commit a9f8696d
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=a9f8696d4be5228de9d1d4f0e9f027b64d77dab6



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Compilation fails when KVM is selected and ARM64_SVE isn't.

The root cause is that sve_cond_update_zcr_vq is not defined when
ARM64_SVE is not selected. Fix it by adding an empty definition
when CONFIG_ARM64_SVE=n.

Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
[maz: simplified commit message, fleshed out dummy #define]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1617183879-48748-1-git-send-email-tanxiaofei@huawei.com


Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>