hw/loongarch/virt: Rename filename acpi-build with virt-acpi-build

File acpi-build.c is relative with virt machine type, rename it with
virt-acpi-build.c

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>

hw/loongarch/meson.build

@@ -4,6 +4,6 @@ loongarch_ss.add(files(
 ))
 common_ss.add(when: 'CONFIG_LOONGARCH_VIRT', if_true: files('fw_cfg.c'))
 loongarch_ss.add(when: 'CONFIG_LOONGARCH_VIRT', if_true: files('virt.c'))
-loongarch_ss.add(when: 'CONFIG_ACPI', if_true: files('acpi-build.c'))
+loongarch_ss.add(when: 'CONFIG_ACPI', if_true: files('virt-acpi-build.c'))
 
 hw_arch += {'loongarch': loongarch_ss}