KVM: arm64: nv: Add trap forwarding for ERET and SMC

Honor the trap forwarding bits for both ERET and SMC, using a new
helper that checks for common conditions.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Co-developed-by: Jintack Lim <jintack.lim@linaro.org>
Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240419102935.1935571-7-maz@kernel.org


Signed-off-by: Marc Zyngier <maz@kernel.org>