ACPI: utils: Fix white space in struct acpi_handle_list definition

Fix inadvertently introduced white space damage in the struct
acpi_handle_list definition.

No functional impact.

Fixes: 2e57d10a

 ("ACPI: utils: Dynamically determine acpi_handle_list size")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>