target/arm: Mask PMOVSR writes based on supported counters

target/arm: Mask PMOVSR writes based on supported counters

This is an amendment to my earlier patch:
    commit 7ece99b17e832065236c07a158dfac62619ef99b
    Author: Aaron Lindsay <alindsay@codeaurora.org>
    Date:   Thu Apr 26 11:04:39 2018 +0100

	target/arm: Mask PMU register writes based on PMCR_EL0.N

Signed-off-by: Aaron Lindsay <alindsay@codeaurora.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20181010203735.27918-3-aclindsa@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>