arm64: KVM: Force undefined exception for Guest SMC intructions

The SMC-based PSCI emulation for Guest is going to be very different
from the in-kernel HVC-based PSCI emulation hence for now just inject
undefined exception when Guest executes SMC instruction.

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: marc Zyngier <marc.zyngier@arm.com>