x86: qemu: Enable ACPI table generation by default

Now that ACPI is supported on QEMU, enable it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

configs/qemu-x86_defconfig

@@ -4,6 +4,7 @@ CONFIG_SMP=y
 CONFIG_MAX_CPUS=2
 CONFIG_GENERATE_PIRQ_TABLE=y
 CONFIG_GENERATE_MP_TABLE=y
+CONFIG_GENERATE_ACPI_TABLE=y
 CONFIG_FIT=y
 CONFIG_BOOTSTAGE=y
 CONFIG_BOOTSTAGE_REPORT=y