target/arm: Use aarch64_cpu_register() for 'host' CPU type

target/arm: Use aarch64_cpu_register() for 'host' CPU type

Use the aarch64_cpu_register() machinery to register the 'host' CPU
type.  This doesn't gain us anything functionally, but it does mean
that the code for initializing it looks more like that for the other
CPU types, in that its initfn then doesn't need to call
arm_cpu_post_init() (because aarch64_cpu_instance_init() does that
for it).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Alexander Graf <agraf@csgraf.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220204165506.2846058-3-peter.maydell@linaro.org