arm64: Add BTAC/LinkStack sanitizations for Kryo cores

Kryo cores are exposed to two vulnerabilities due to subroutine return
(called LINK-STACK) and branch target predictors.
These two issues can be mitigated through software workarounds.

Kernel:
 - Apply LINK-STACK mitigation which is to issue 16 nested BL instructions
   on process context switch 'cpu_do_switch_mm()' where ASID changes.
 - Apply psci based branch predictor invalidation.

use the kryo core detection routine (based on MIDR) from the
commit bb48711800e6d ("arm64: cpu_errata: Add Kryo to Falkor 1003 errata")
by Stephen Boyd <sboyd@codeaurora.org>.

Change-Id: I81e8e72e7fa219f12dfe8ec39836eb8eb3c4c7b0
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>