ARM64/errata: Ensure vulnerable CPUs are actually flagged on `is_spectrev2_safe()`

This updates logic introduced by commit 6deba989 to ensure affected CPUs
are properly flagged as affected by Spectre BHB, either by SMCCC or PSCI
methods of detection.

Signed-off-by: Albert I <kras@raphielgang.org>
[jjpprrrr: change !(A || B) to (!B && !A) to take advantage of short
circuit when B (PSCI) is the more likely case]
Signed-off-by: Chenyang Zhong <zhongcy95@gmail.com>
Change-Id: I1da47886c5e1f1331ece977813ae3ec832d13af3
1 file changed