arm64: kpti: Add NVIDIA's Carmel core to the KPTI whitelist

NVIDIA Carmel CPUs don't implement ID_AA64PFR0_EL1.CSV3 but
aren't susceptible to Meltdown, so add Carmel to kpti_safe_list[].

Signed-off-by: Rich Wiley <rwiley@nvidia.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>