target-arm: A64: Introduce aarch64_banked_spsr_index() Add aarch64_banked_spsr_index(), used to map an Exception Level to an index in the banked_spsr array. Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com> Message-id: 1400980132-25949-13-git-send-email-edgar.iglesias@gmail.com Signed-off-by: Peter Maydell <peter.maydell@linaro.org>