ANDROID: kvm: arm64: Move SPE/TRBE availability check to VCPU load

At the moment, we check the availability of SPE/TRBE on the given
CPU (i.e, SPE is implemented and is allowed at the host) during
every guest entry. This can be optimized a bit by moving the
check to vcpu_load time and recording the availability of the
feature on the current CPU via a new flag.

Bug: 174685394
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Alexandru Elisei <Alexandru.Elisei@arm.com>
Cc: James Morse <james.morse@arm.com>
Link: https://lore.kernel.org/linux-arm-kernel/20210405164307.1720226-7-suzuki.poulose@arm.com/


Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Change-Id: Ifa6efb97532667b4c4999865031a9bb8576a8100