efi: x86: Correct the condition for installing ACPI tables

It is not always the case that U-Boot builds the ACPI tables itself. For
example, when booting from coreboot, the ACPI tables are built by
coreboot.

Correct the Makefile condition so that U-Boot can pass on tables built
by a previous firmware stage.

Tidy up the installation-condition code while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
index 58d4e13..ad719af 100644
--- a/lib/efi_loader/efi_setup.c
+++ b/lib/efi_loader/efi_setup.c
@@ -321,11 +321,11 @@
 	if (ret != EFI_SUCCESS)
 		goto out;
 #endif
-#ifdef CONFIG_GENERATE_ACPI_TABLE
-	ret = efi_acpi_register();
-	if (ret != EFI_SUCCESS)
-		goto out;
-#endif
+	if (IS_ENABLED(CONFIG_ACPI)) {
+		ret = efi_acpi_register();
+		if (ret != EFI_SUCCESS)
+			goto out;
+	}
 #ifdef CONFIG_GENERATE_SMBIOS_TABLE
 	ret = efi_smbios_register();
 	if (ret != EFI_SUCCESS)