arm64: Implement branch predictor hardening for Falkor

Falkor is susceptible to branch predictor aliasing and can
theoretically be attacked by malicious code. This patch
implements a mitigation for these attacks, preventing any
malicious entries from affecting other victim contexts.

Change-Id: Ieb49196c23582c3174f778891ff2ab7cdc96be54
Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
[will: fix label name when !CONFIG_KVM and remove references to MIDR_FALKOR]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Git-commit: ec82b567a74fbdffdf418d4bb381d55f6a9096af
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux


[neeraju@codeaurora.org: resolve merge conflicts.
 Take only qcom_link_stack_sanitization() definition]
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>