hw/microblaze: Build files once

Previous commit removed the last target-specific use in
hw model units, we can now build them once.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-ID: <20260106235333.22752-7-philmd@linaro.org>

hw/microblaze/meson.build

@@ -4,4 +4,4 @@ microblaze_ss.add(when: 'CONFIG_PETALOGIX_S3ADSP1800', if_true: files('petalogix
 microblaze_ss.add(when: 'CONFIG_PETALOGIX_ML605', if_true: files('petalogix_ml605_mmu.c'))
 microblaze_ss.add(when: 'CONFIG_XLNX_ZYNQMP_PMU', if_true: files('xlnx-zynqmp-pmu.c'))
 
-hw_arch += {'microblaze': microblaze_ss}
+hw_common_arch += {'microblaze': microblaze_ss}