target/arm/sme: Unify set_pstate() SM/ZA helpers as set_svcr()

target/arm/sme: Unify set_pstate() SM/ZA helpers as set_svcr()

Unify the two helper_set_pstate_{sm,za} in this function.
Do not call helper_* functions from svcr_write.

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: 20230112102436.1913-8-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>