target/arm: Implement new do_transaction_failed hook

Implement the new do_transaction_failed hook for ARM, which should
cause the CPU to take a prefetch abort or data abort.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 1504626814-23124-4-git-send-email-peter.maydell@linaro.org