target/arm/sme: Reorg SME access handling in handle_msr_i()

target/arm/sme: Reorg SME access handling in handle_msr_i()

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20230112102436.1913-2-philmd@linaro.org
Message-Id: <20230112004322.161330-1-richard.henderson@linaro.org>
[PMD: Split patch in multiple tiny steps]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit 535ca76425fc1ffa4311b3a47518b06c596a55c6)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>