target/arm: Avoid an extra temporary for store_exclusive

target/arm: Avoid an extra temporary for store_exclusive

Instead of copying addr to a local temp, reuse the value (which we
have just compared as equal) already saved in cpu_exclusive_addr.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Message-id: 20170908163859.29820-1-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>