target/arm: Fill in the WnR syndrome bit in mte_check_fail

target/arm: Fill in the WnR syndrome bit in mte_check_fail

According to AArch64.TagCheckFault, none of the other ISS values are
provided, so we do not need to go so far as merge_syn_data_abort.
But we were missing the WnR bit.

Tested-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200813200816.3037186-3-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>